When asked about Trump's previous praise for Mr Comey, Ms Sanders said that things "change".

"I think you're looking at two very different positions. The president was wearing a very different hat at that time - he was a candidate, not the president," she said.

"Those circumstances certainly change when you become the president."

Comey reportedly found out he was sacked when he saw the news on TV, midway through addressing his team, and initially thought it was a prank organised by his staff.

He was then handed a note informing him that a letter had been delivered to the FBI office in Washington DC.

Asked whether the manner in which he was sacked was appropriate, Sanders said the president was simply following protocol.

"He followed the proper protocol in that process, which is hand written notification," she said.

"No matter how you fire someone it's never an easy process, so the president felt it was best to follow protocol." 

In Trump's letter to Comey he thanked him for apparently informing him on three separate occasions that the FBI had privately exonerated the president in its Russia probe.

The apparent assurances raised eyebrows over propriety. Asked whether the White House was concerned over those conversations, Sanders was brief: "No." 

Sarah Huckabee Sanders, deputy White House press secretary, has told reporters that President Trump had doubts about Mr Comey's position since last year.

"He'd lost confidence in Director Comey, and frankly he had been considering letting Director Comey go since the day he was elected," Ms Sanders said.

But she denied that President Trump told the deputy attorney general to write the memo containing a reccomendation to sack Comey.

"He asked them for their recommendation... he asked them to put their recommendation in writing," she said. "But they came to him."

She accused Comey of "throwing a stick of dynamite" into the Department of Justice and committing "atrocities".

Attorney general Jeff Sessions and deputy attorney general Rod Rosenstein met with Trump at the White House on Monday and advised him to sack Comey, according to an unconfirmed report, external on by McClatchy White House correspondent Anita Kumar. 

"Hours later, Trump had made his decision: He fired Comey in a terse letter that didn’t mention the Clinton investigation sent to FBI headquarters by his former longtime bodyguard Keith Schiller, now director of Oval Office operations. He then called a handful of senators of both parties to inform them of the news."

As the White House prepares to brief journalists, a small but colourful protest is going on outside.

Here's what Vice President Mike Pence had to say earlier on the need for "a fresh start at the FBI", and how Mr Trump's decision to dismiss Director Comey showed "strong leadership".

Barbara Plett Usher
BBC News, Washington

The rare visit by the Russian Foreign Minister was impossible to separate from the political drama over the firing of the FBI director.

Sergei Lavrov was grilled by journalists in a news conference after his meetings - about the impact of this latest twist in the investigation into Russia's alleged meddling in the election. 

He impatiently dismissed any connection and said President Trump hadn't raised the issue with him. 

Speaking through a translator, he also said that despite recent tensions he thought Moscow would get along better with this administration than the previous one .

Here's that video from earlier, when Mr Trump made his first comments about the issue on camera.

With him is Henry Kissinger - Richard Nixon's former Secretary of State, who Mr Trump called "a friend of mine for a long time."

"He was not doing a good job, very simply", the president said of Mr Comey's departure.

Image source, Getty Images

Conservative former senator Rick Santorum told CNN that Comey was to blame for his dismissal.

"I think James should have been fired on day one," he said, adding that he was "excited Donald Trump finally got around to the doing the right thing".

"I believe he was fired because he sought fame," he said.

"He provided info about who was being investigated. He put himself in the political limelight."

The BBC's Rajini Vaidyanathan and Anthony Zurcher are at the Capitol building and taking readers' questions.

Watch live and post your own question for Anthony on Facebook.

Image source, EPA

The official White House read out on the meeting between President Trump and Russia's foreign minister say Mr Trump asked Russia to "rein in the Assad regime" in Syria.

"President Trump emphasised the need to work together to end the conflict in Syria, in particular, underscoring the need for Russia to rein in the Assad regime, Iran, and Iranian proxies," the White House statement said. 

Mr Trump also brought up the Ukraine conflict and the Middle East, and reiterated his wish for a better relationship between the US ad Russia.

DOJ spokeswoman Sarah Flores has had a quick change of opinion.

After "100%" denying that Comey had requested more money for the Russia/ Trump campaign investigation, she now says he requested "more resources" not "more money".

Several Twitter users point out that in the government resources equal money.

Image source, AFP

During his press conference, Russia's foreign minister, Sergei Lavrov, denied his country interfered in US politics.

He said any reports of Russian meddling in US politics were "fabrications", according to the AFP news agency.

"As for the talk and noise raised around our relations, around fabrications saying that we are in charge of the domestic politics (of the US), of course we have observed this absolutely abnormal background on which our relations are developing," he said.

Democratic National Committee Chairman Tom Perez is speaking to protesters gathered outside the White House.

He is calling for a special prosecutor, while the demonstrators cheer their approval.

Reuters news agency quotes a White House official as giving four possible names for the interim FBI director:

• Current acting director, Andrew McCabe
• Assistant director, Paul Abbate
• Chicago special agent in charge, Michael J Anderson
• Richmond, VA, special agent in charge, Adam Lee

All four are senior FBI officials and the interview process is being run by the justice department, the news agency said.

CBS News managed to grab a moment with Russian President Vladimir Putin, in full ice hockey gear, before he made his way on to the rink for a game.

Mr Putin said "there will be no impact" on US-Russia relations from the Comey firing, and the question is "very funny".

"We have nothing to do with that," he said of Mr Comey's dismissal.

The FBI website still lists James Comey as the FBI director.

Nick Akerman, who served as an assistant prosecutor for the Watergate Special Prosecution Force, has broken down the similarities and differences between yesterday's events and Nixon's firing of the prosecutor investigating the Watergate break-in. 

"The obvious parallel to the October 1973 Saturday Night Massacre is that the President is firing the person in charge of an investigation into himself," Akerman says.  

But he says there are also several differences.

First, the Watergate Special Prosecution Force was an ad hoc group, and when Archibald Cox was fired by Nixon, people wondered if the investigation itself would be dissolved. The FBI is a permanent institution, and there is no risk it will vanish.

Akerman argues that Cox had a cleaner record than Comey, who he says broke protocols on several occasions throughout the investigation into Clinton's emails.

Image source, Reuters

Russian Foreign Minister Sergei Lavrov has been speaking after his meeting with Trump.

"We have to start from a very low level of relations... our task is to remove all those barriers," he told the assembled media in Washington - in Russian. 

All of his remarks were delivered in his native language. 

He said they had discussed the so-called "safe zones" in Syria.

What are safe zones?