BBC political editor Laura Kuenssberg was loudly heckled and shouted down after suggesting to UKIP's leader, Paul Nuttall, that he was trying to blame the prime minister for the bomb attack in Manchester.

Mr Nuttall had to intervene and urge party members at UKIP's manifesto launch to "be respectful".

The UKIP leader denied "accusing the prime minister", adding that "politicians had been weak on this issue for many, many years".

But he criticised Mrs May's time as home secretary:

The threat level "will remain at critical and the public should remain vigilant", Prime Minister Theresa May has said.

Speaking after a meeting of the emergency committee Cobra, Mrs May said that at the Nato summit she will "make clear to President Trump that intelligence that is shared between our law enforcement agencies must remain secure".

Norman Smith
Assistant political editor

Paul Nuttall seems to be trying to move UKIP into different terrain, away from a focus on Brexit and immigration and towards integration.

It's a highly-charged issue, particularly the week after the Manchester attack.

They are trying to position themselves as the party to tackle fundamentalism.

UKIP pledges an £11bn per year increase in spending on the NHS and adult social care by the end of the next Parliament.

Leader Paul Nuttall says this is equivalent to the reduction the party is planning to make to the overseas aid budget.

Paul Nuttall says UKIP will address problems that "the Westminster chatterati would rather ignore".

He accuses Theresa May of having "presided over cuts" to the police and armed forces, while "no progress whatever was made reducing the level of immigration in order to give social cohesion a chance to advance".

Responding to the latest migration figures, Mr Nuttall claims: "This morning it was announced we have added a city the size of Hull to our population in the last year."

He adds: "It was also a dereliction of duty to allow jihadis to return to this country including, it seems, Monday night's terrorist."

Paul Nuttall says UKIP's manifesto addresses security, with pledges of "20,000 extra police officers, 20,000 extra troops, 7,000 extra prison officers and 4,000 extra border guards".

He says it was "quite right" that election campaigning was paused but right for UKIP to publish its manifesto now.

"It is not enough to light candles or signal our upset on social media," he says. "When you are a leader of a political party you have a duty to set out how you would protect the people of your country."

"There is no magic formula for turning back the tide of Islamic fundamentalism," he tells his audience. It needs "the political will to challenge communities [and] secure our borders".

He says he makes "no apologies" for calling "radical Islam a cancer in our society".

UKIP leader Paul Nuttall opens his speech with "condolences to those who have lost family members and friends due to a cruel and evil act of terrorism in Manchester on Monday night".

He adds:

Net migration to Britain fell to 248,000 last year but is still more than double the government's target level.

The prime minister has stuck by David Cameron's pledge to cut the annual level of net migration to below 100,000, but has not put a time-frame on it.

The last time overall net migration was below 250,000 was in the year to March 2014. According to the Office for National Statistics, the recent fall was due to a rise in the number of people leaving the country, mainly European Union citizens, and a fall in the number of people arriving in Britain.

Campaigning is gradually getting back into gear after the tragic events in Manchester.