British Prime Minister David Cameron told the Leader of the Opposition Jeremy Corbyn, who is facing a revolt from MPs, to step down in the national interest.
"It might be in my party's interests for him to sit there, it's not in the national interests and I would say, for heaven's sake man, go," Cameron said to Corbyn at Prime Minister's Questions in Parliament.
Labour MPs voted against Corbyn in a no-confidence motion by 172 to 40 after dozens of members of his frontbench team stepped down in recent days. But Corbyn has refused to go.
Centrists have criticised the veteran socialist's leadership for months but the row came to a head when he was accused of not campaigning enough in Britain's EU referendum, which delivered a shock Leave result last week.
Corbyn was elected Labour leader last year on a wave of support from grassroots Labour members but has struggled to build broad support among MPs.
Cameron has said he will step down in the wake of the referendum and will leave office when his successor is chosen in early September.
Former leader Ed Miliband and Labour grandees include Dame Tessa Jowell and Dame Margaret Beckett also called for Corbyn to resign.
Tom Watson, the deputy leader of the Labour Party, has told the BBC that Corbyn was not willing to discuss the possibility of his resignation and that he had been making attempts to oversee his exit.
He added that he will not challenge Corbyn for the leadership.
- additional reporting AFP