Sir Keir Stamer has insisted the "vast majority" of Labour MPs support him and want him to continue doing his job as prime minister.

He was speaking to the Sunday Times at the end of a week in which speculation has grown that the possibility of him facing a challenge to his leadership from within his own party was rising.

Sir Keir told the paper "in politics, you get this sort of thing all of the time, there is always talk".

He added "what you never hear from are all the people who are supportive, loyal and just want to get on with the job. And that is the vast majority of people in the Parliamentary Labour Party."

"They're pleased to be in power," said Sir Keir, speaking about what said was most Labour MPs.

"They've waited a long time to be in power. And they just want to get on with their job. They don't make a lot of noise about it. They don't talk to journalists about it. It's really important that is reflected in these debates."

He has faced calls from opposition parties to resign, and criticism from within his own party, after it emerged that UK security officials had flagged concerns about giving vetting clearance to his choice to be the UK's ambassador the United States, Lord Mandelson.

Sir Keir told MPs this week that the security officials had recommended against vetting approval being granted but that had not been passed on to him.

Speaking to the Sunday Times he said he did not regret his decision, last week, to sack the most senior civil servant in the Foreign Office, Sir Olly Robbins, who had not informed him about the security vetting concerns.

"When there's a double red flag not to give clearance and [showing] high concern, then I'm sorry. I'm sorry. But I do not accept the argument that that is something which should not be told to the prime minister," Sir Keir said.

Sir Olly Robbins told MPs this week that he had not been told that there was a recommendation to deny Lord Mandelson security clearance, only that officials were "leaning against" it. Sir Olly decided to approved the vetting subject to mitigations being put in place.

Sir Keir dismissed the suggestion he should have done more to inquire about the outcome of Lord Mandelson's vetting process.

"When I'm told there's security clearance, should I go back and quiz officials and say, 'Are you telling me the truth?'"

"If I questioned every bit of information put in front of me I would never get anything done. The number of decisions that have to be made each day is huge."

The prime minister told the paper he wanted to focus on the wars in Ukraine and Iran rather than speculation about possible challenges to his leadership, as the implications for the UK of those conflicts was the most important issue facing the country.

"This is the urgent issue of our time," Sir Keir told the paper, "this is going to reshape our country."

"The conflict with Iran has not just been fought out in Iran. There are increasingly the use of proxies in this country. Of course there's lots of discussion in parliament about who's up, who's down and all the rest of it. But this is the serious work of being the prime minister."