As many as 20 people were killed when a civilian convoy was shelled by Russian troops in Ukraine's north-eastern Kharkiv region, a top local official says, citing preliminary information.

Oleh Synehubov says the attack happened in the town of Kupiansk, close to the Russian border. He did not specify when exactly it happened.

"The occupiers attacked civilians who tried to escape from the shelling. This is cruelty that has no justification," Synehubov wrote in a post on social media.

The reported attack has not been independently verified.

On Friday, 30 people died when Russian rockets hit a civilian convoy in the southern Zaporizhzhia region, local officials said.

Russia blamed Ukraine for that attack.

Image source, Reuters

Mongolia says it is ready to issue residency permits to all Russian arrivals who request them.

It comes amid a Russian exodus to neighbouring countries, triggered by President Vladimir Putin’s announcement of a partial military mobilisation on 21 September.

Mongolian immigration agency chief Nerguin Uuganbayar did not specify the permits' duration. He said 6,268 Russians had entered via Altanbulag, a border town, in the past week.

The Russian call-up affects reservists – not conscripts – but alarm has spread among Russian men of fighting age.

Russians can enter Mongolia visa-free and stay for 30 days, then request an extension.

Kazakhstan reported that 98,000 Russians had arrived since Putin’s announcement.

In the Caucasus, an enormous queue of Russian cars developed at Georgia’s border. Georgia said about 10,000 Russians were arriving every day – double the previous average number.

Finland has shut its border to most Russian visitors, though there are some exemptions, for example for family reunions and work. Poland and Baltic states Estonia, Latvia and Lithuania made the same move earlier.

More on the rapidly developing situation around the key town of Lyman in the eastern Donetsk region.

A video has now emerged purportedly showing Ukrainian soldiers raising the country's national blue-and-yellow flag at the entrance to the town, where thousands of Russian troops are reported to be encircled.

In the footage - posted by President Volodymyr Zelensky's head of office Andriy Yermak - two soldiers can be heard saying in Ukrainian: "[Today is] 1 October. We're unfolding our state flag and putting it on our land.

"Lyman. All will be Ukraine," they say, hailing Ukrainian paratroopers.

Ukraine's military has so far not officially confirmed that Lyman has been recaptured.

Hugo Bachega
Ukraine correspondent in Kyiv

Ukrainian officials say nothing changes with President Putin's announcement. They describe everything – from the so-called referendums to the annexation speech – as a farce with no legitimacy, and say they are going ahead with their offensive to retake all territory that has been invaded.

The four regions that Russia says it is incorporating are only partially under occupation – Donetsk and Luhansk, in the east, and Zaporizhzhia and Kherson, in the south.

Fighting is still happening in many areas, including around the key town of Lyman, in Donetsk.

Hours after Putin’s speech, Ukraine’s military said its forces had completely encircled the town, which has been used as a key logistics hub by Russian forces.

The recapture of this town would be a significant gain for Ukraine, as it would put its forces in a position to reclaim more territory in Donetsk and Luhansk, territories that Russia claims to be “liberating”.

Image source, Getty Images

The large Russian grouping in Lyman is "surrounded" and settlements around the town have been recaptured, says Serhiy Cherevatyi, a spokesman for Ukraine's forces in the east.

He told Ukrainian TV "our data shows that about 5,000-5,500 Russian troops were in Lyman”, but he said that number was lower now because of recent "active combat action" in which "many" Russian soldiers were killed or wounded.

Cherevatyi said all continuing breakthrough attempts by Russian troops had "failed". He also spoke about the importance of Lyman, which, if conquered by Ukrainian troops, would allow them to advance on Kreminna and Severodonetsk, both of which are key Russian-held strongholds.

"It’s also very important psychologically, because – as President Zelensky said yesterday – Ukraine’s armed forces are beginning to dictate their will – and not just defend."

Yet the military operation "is not over yet," he concluded.

More now on the situation around Ukraine's eastern city of Lyman, in Donetsk region.

Russian troops there have asked their superiors to leave the city - but this request was rejected, a senior Ukrainian official says.

Luhansk regional head Serhiy Haidai says the Russian soldiers now have only two choices: to try to break through or surrender.

Haidai adds that almost all withdrawal and ammunition supply routes are now cut off to Lyman.

The claim has not been independently verified.

On Friday Denis Pushilin, the Russian-installed leader of Donetsk region, said Lyman was "semi-encircled " and Russian forces were holding out "with the last of their strength".

In its regular intelligence update, external on the situation in Ukraine, the UK Ministry of Defence says Russian forces "almost certainly" struck a humanitarian convoy yesterday - an attack which Ukraine said killed at least 30 people in civilian vehicles.

The munition used in the strike "was likely a Russian long-range air defence missile being used in a ground attack role," the MoD statement says.

It adds that Russia’s stock of such missiles is likely limited, and that they're a "high-value resource" designed to shoot down aircraft and missiles, rather than for use against ground targets.

According to the MoD, the use of these missiles in a ground attack role indicates overall shortages of munitions, particularly longer-range precision missiles.

The strike occurred in the region of Zaporizhzhia, which Vladimir Putin declared to be part of Russia yesterday. The MoD briefing concludes:

Turkey's foreign ministry has condemned Russia's declared annexation of four occupied regions of Ukraine - echoing the condemnation by Turkey's Nato allies on Friday.

A ministry statement says Turkey "did not recognise Russia’s annexation of Crimea in an illegitimate referendum in 2014 and has emphasised its strong support to Ukraine’s territorial integrity, independence and sovereignty on every occasion.

"In accordance with this stance adopted in 2014, we reject Russia’s decision to annex the Donetsk, Luhansk, Kherson and Zaphorizhzhia regions of Ukraine.

"This decision, which constitutes a grave violation of the established principles of international law, cannot be accepted."

Turkey has tried to mediate between Ukraine and Russia, and its diplomacy with the UN led to the recent deal to free up Ukrainian grain exports via the Black Sea.

Image source, Reuters

Since capturing Lyman in late May, Russian troops have transformed the city in the Donetsk region into a major logistics hub for troop deployments and ammunition supplies.

The city is also a key railway centre, connecting the Donetsk, Luhansk and Kharkiv regions in Ukraine's east and north-east.

As many as 5,000 Russian troops could be currently trapped in Lyman, and its recapture by Ukraine would be one of Russia's worst military defeats since the start of its invasion on 24 February.

It would allow Ukrainian troops to completely mop up the northern part of the Donetsk region and move further into neighbouring Luhansk region.

Ukraine says its troops have recaptured two villages on the outskirts of Lyman.

Image source, Reuters

President Joe Biden has warned Russia that the United States will not be intimidated by reckless threats after Vladimir Putin declared the annexation of four occupied regions of Ukraine.

President Biden condemned his Russian counterpart's "reckless words and threats", but added that Putin was "not going to scare us".

"America and its allies are not going to be intimidated," Biden said at the White House.

He then addressed the Russian leader directly, pointing his finger into the camera, and said that "America's fully prepared, with our Nato allies, to defend every single inch of Nato territory".

"Mr Putin, don't misunderstand what I'm saying: every inch."

Shortly after, Biden's top national security official said there was a chance of Moscow resorting to nuclear weapons, but there did not appear to be an imminent threat.

Steve Rosenberg
BBC Russia editor

This week, one Russian newspaper, Moskovsky Komsomolets, concluded: "Vladimir Putin has nowhere to retreat. So, he'll continue to attack."

Cue St George's Hall of the Kremlin Palace and the controversial signing ceremony in front of MPs, senators and officials.

Vladimir Putin's decision to annex the four Ukrainian territories ("incorporate" in Kremlinspeak) is the Russian president's latest offensive in his battle with Ukraine and the West.

Through annexation, the Kremlin is trying to change the facts on the ground (at a time when Russia has been losing ground in Ukraine).

Mr Putin wants to present a fait accompli to Kyiv and to the West.

It raises the stakes considerably in the president's standoff with Ukraine and the Western world.

Read the rest of the piece here.

Image source, Reuters

The director general of Ukraine's Russian-occupied Zaporizhzhia nuclear power plant was detained by a Russian patrol, Ukraine's state nuclear agency Energoatom said today.

Ihor Murashov was arrested while driving from the facility to the nearby town of Enerhodar on Friday afternoon. Murashov was reportedly blindfolded and taken to an unknown location.

Energoatom has appealed to the International Atomic Energy Agency to demand his immediate release.

Zaporizhzhia is Europe's biggest nuclear plant and repeated shelling of the site has raised the risk of a nuclear disaster. Russia and Ukraine blame each other for the shelling.

Thank you for joining us as we continue to follow the latest developments in Russia's invasion of Ukraine.

Here is a reminder of what has been happening in the last 24 hours:

• In a speech on Friday Russia's President Vladimir Putin announced that four areas of Ukraine were now "forever" Russian territory, after referendums in the areas which have been deemed a "sham" by Ukraine and its allies
• Ukraine's President Volodymyr Zelensky responded by applying to Nato for fast-tracked membership
• Mr Zelensky said Ukraine would fight to liberate all of its territory, saying the path for his nation was difficult but clear, and he was confident of victory
• Reports say the Ukrainian army is close to re-taking the town of Lyman, which lies in a key strategic position in the east of the country. There is said to be heavy fighting in the area
• At least 30 people were killed and almost 100 more were wounded in a Russian rocket strike on a civilian convoy near Zaporizhzhia on Friday