Boris Johnson censored questions from journalists over the Dominic Cummings controversy, saying he would not allow two of the Government's top coronavirus advisers to comment on the matter.

The Prime Minister was peppered with questions about his decision not to sack his chief aide, who Durham Constabulary said may have committed "a minor breach" of rules when he drove to Barnard Castle under lockdown.

But Mr Johnson said he wanted to "draw a line" under the Cummings affair, and said he would not allow Government chief scientific adviser Sir Patrick Vallance and chief medical officer for England Professor Chris Whitty to answer questions on the row to "protect them" from a "political argument".

It was their first appearance at the daily Downing Street briefings since before the story broke at the weekend, although they were seen leaving Downing Street shortly before the press conference on Monday.

Mr Johnson said on Thursday evening: "I've said quite a lot on this matter already and what I also note is that what Durham police said was that they were going to take no action and that the matter was closed.

"And I intend to draw a line under the matter, as I said yesterday to the Parliamentary Liaison Committee."

Speaking to the BBC's Laura Kuenssberg, who raised the issue, he added: "I know that you've asked Chris and Patrick but I'm going to interpose myself if I may and protect them from what I think would be an unfair and unnecessary attempt to ask any political questions.

"It's very, very important that our medical officers and scientific advisers do not get dragged into what I think most people would recognise is fundamentally a political argument."

Mr Johnson jumped in again when questions were aimed at Sir Patrick and Prof Whitty about Mr Cummings, telling the Downing Street briefing: "It's very important our advisers are protected from being dragged into political controversy."

Asked by Sky News' Sam Coates if they were comfortable with the PM telling them they could not answer questions about Mr Cummings - suggesting a "nod or a shake of the head" would affirm - Prof Whitty replied: "The desire to not get pulled into politics is far stronger on the part of Sir Patrick and me than it is in the Prime Minister."

Sir Patrick added: "I'm a civil servant, I'm politically neutral, I don't want to get involved in politics at all."