Shadow foreign secretary Hilary Benn has been sacked from the shadow cabinet amid claims he was encouraging ministers to resign should Jeremy Corbyn ignore a vote of no confidence.
Labour's leader faces a vote of no confidence over claims he was "lacklustre" during the EU referendum.
A Labour source told the BBC Mr Corbyn had "lost confidence" in Mr Benn.
Mr Benn said there was "widespread concern" about Mr Corbyn's "leadership and his ability to win an election".
He added: "There is no confidence to win the next election if Jeremy continues as leader.
"In a phone call to Jeremy I told him I had lost confidence in his ability to lead the party and he dismissed me."
