PETER MANDELSON should never have been appointed as ambassador to the US, Foreign Secretary Yvette Cooper admitted today.

However, Ms Cooper declined to back the under-fire Prime Minister who did the appointing as the row over the release of government messages relating to the episode continued.

Speaking during a trip to Beijing, she ducked attempts to get her to endorse the view that Sir Keir Starmer is a strong and effective leader.

Ms Cooper instead said: “I’m in China pursuing issues around international security which follows on from the Prime Minister’s visit here to China with President Xi earlier this year.”

She added that “Peter Mandelson should never have been appointed as ambassador to the United States.”

The Foreign Secretary is understood to be one of those very lukewarm about Sir Keir continuing in Downing Street for much longer.  

She herself came third in the 2015 Labour leadership race won by Jeremy Corbyn.

SNP MP Kirsty Blackman also called for Labour Scottish Secretary Douglas Alexander to quit yesterday over his “sycophantic and pitiful messages” to Mandelson after welcoming his appointment at the time as “good news for you, for the government and for the country.”