Britain's ambassador to the US has admitted Keir Starmer is 'on the ropes' over the Peter Mandelson scandal and could be ousted by Labour MPs next month.

Christian Turner, who replaced Lord Mandelson as the UK's top diplomat in Washington DC, suggested the Prime Minister could be 'brought down' by the row.

In leaked remarks, which will be hugely embarrassing for Sir Keir, Sir Christian outlined how Labour MPs could 'remove' the PM from Downing Street after local elections on 7 May.

He also played down the so-called 'special relationship' between the UK and US, saying America's only 'special relationship' is 'probably Israel'.

The emergence of a recording of Sir Christian's remarks, said to have been made in mid-February shortly after he started in post, is a massive headache for the PM and comes amid King Charles' state visit to America this week.

Sir Keir has vowed to stay on as PM into the 2030s, despite facing mounting unrest among Labour MPs over his appointment of Lord Mandelson and his handling of the resultant scandal.

He has also repeatedly defended the 'special relationship' between Britain and America in the face of US President Donald Trump's frequent attacks on him over the Iran war.

Sir Christian was appointed as Britain's new ambassador to the US in December last year after Lord Mandelson, who was Sir Keir's initial pick for the job, was sacked over his links to paedophile financier Jeffrey Epstein. 

Shortly after he formally took up the role at the beginning of February, Sir Christian is revealed to have told UK students visiting Washington that it was 'extraordinary' the Epstein scandal 'hasn't touched anybody' in the US.

In a recording of the remarks, shared with the Financial Times, the long-serving diplomat noted how the scandal had 'brought down a senior member of the royal family [Andrew Mountbatten-Windsor], a British ambassador to Washington, potentially the Prime Minister, and yet here in the US, it really hasn't touched anybody'.

Sir Christian added the row over his predecessor Lord Mandelson's appointment as US ambassador was a 'crisis' that 'has nearly brought down the Government and ended the Prime Minister's tenure'.

Of Sir Keir, he said 'at one stage he was pretty clearly on the ropes' and the PM's future looked 'quite touch and go'.

'The moment I would look to is the May elections,' Sir Christian added. 'If Labour does very badly... I suspect the party will be able to go over that threshold and remove him - seems to me to be the conventional thinking.'

He continued: 'If they do OK, he might carry on going... That's just for me as a citizen speculating because I have to serve whomever is there.' 

Sir Christian is also revealed to have said he disliked the phrase 'special relationship' to describe UK-US ties, saying it was 'quite nostalgic, it's quite backwards-looking, and it has a lot of baggage about it'.

'I think there is probably one country that has a special relationship with the United States - and that is probably Israel,' he added.

Sir Christian's remarks are said to have been made during a question-and-answer session with students on diplomacy and politics and were never intended as an on-the-record statement of Government policy.

A Foreign Office spokesman said: 'These were private, informal comments made to a group of UK sixth-form students visiting the US in early February. 

'They are certainly not any reflection of the UK Government's position.'