Hilary Benn has been sacked as shadow foreign secretary by Jeremy Corbyn amid fears he planned to spearhead a coup against the Labour leader.
Mr Benn, 62, is the son of former Labour politician Tony Benn and had served in the role since May 2015.
Currently, the Mr Corbyn faces a no confidence vote over his "lacklustre" campaign for a remain vote.
Reports in newspapers had suggested Mr Benn was encouraging shadow ministers to resign if Mr Corbyn ignored the motion of no confidence.
But in a midnight telephone call, the Leeds Central MP was informed he had been kicked out of the top team.
Mr Benn told the BBC there was widespread concern among Labour MPs and in the shadow cabinet about Mr Corbyn's leadership and his ability to win an election.
"There is no confidence to win the next election if Jeremy continues as leader," he said.
"In a phone call to Jeremy I told him I had lost confidence in his ability to lead the party and he dismissed me."
The party leader has faced accusations from his own MPs that he led a weak campaign in the EU referendum and is facing a motion of no confidence.
Mr Benn was reportedly planning to ask Mr Corbyn to stand down and had asked other senior frontbenchers to quit with him if the leader refused to budge.
Former culture secretary Ben Bradshaw has also been among those calling for Mr Corbyn's resignation and urged the shadow cabinet to act now to "save" the party.
Meanwhile, Wes Streeting, Labour MP for Ilford North, tweeted that there were "no longer good reasons for good people to stay" in the shadow cabinet.