Labour has filed an official complaint about the BBC "orchestrating" the resignation of frontbencher Stephen Doughty on live television.
A spokesman for leader Jeremy Corbyn branded Mr Doughty's announcement during the Daily Politics programme on Wednesday an "unacceptable breach of the BBC's role and statutory obligations".
"By the BBC's own account, BBC journalists and presenters proposed and secured the resignation of a shadow minister on air in the immediate run-up to Prime Minister's Questions, apparently to ensure maximum news and political impact," the spokesman said.
"That was evidently done before any notice of resignation was sent to the Labour leader.
"Such orchestration of political controversy is an unacceptable breach of the BBC's role and statutory obligations."
The dramatic resignation came as Mr Corbyn was engaged in the third day of a protracted reshuffle of his team. Mr Doughty told the programme he was quitting in protest at the sacking of shadow Europe minister Pat McFadden, and also cited policy differences with the leader. Two other ministers also announced their departure around the same time.
In a since-deleted blog post for the BBC's Journalism Academy, the Daily Politics output editor, Andrew Alexander, explained how political editor Laura Kuenssberg had "sealed the deal" for Mr Doughty to resign live on air.
The details sparked a furious response from Labour activists on Twitter, although the BBC has strongly defended the way the story was handled.
"Stephen Doughty had already decided to resign and willingly chose to make his announcement on the programme," a spokesman said.
Mr Doughty has also accused Mr Corbyn's senior aides of "smearing" him, and insisted he sent his resignation letter to the leader before appearing on TV.
Mr Corbyn's spokesman said: "Trust in the impartiality and independence of the BBC is essential. The BBC's role is to report the news impartially, rather than seek to influence events or promote a particular political narrative."