Former BBC chief Mark Thompson has launched a scathing attack on the BBC Trust chairman Lord Patten, accusing him of misleading MPs over large payoffs to departing top brass at the broadcaster.
He claims that Lord Patten and BBC Trustee Anthony Fry wrongly accused him of keeping them in the dark about the nature of the payments when they gave evidence to MPs in July.
Mr Thompson made the accusations in a written submission to the Public Accounts Committee (PAC) ahead of his appearance on Monday.
The BBC Trust responded quickly, calling Mr Thompson's account "bizarre" and rejecting his version of events.
The dispute relates to a series of large payoffs given to departing BBC executives, which the PAC has been tasked with investigating.
Mr Thompson and the BBC Trust disagree about how much the latter knew about a £949,000 payment to outgoing director-general Mark Byford in 2011, which was found to be above what he was contractually owed.
In July, Lord Patten told the PAC that members of the Trust were not fully informed about payment.
Asked how this could be, he said: "If you call a previous director general of the BBC I will be as interested as you are why we didn't know." This was widely interpreted as meaning that they should talk to Mr Thompson.
Mr Fry confirmed to the PAC that the Trust had received a letter from Mr Thompson about the payoffs, but that there was "some disconnect" between their accounts of its contents.
Mr Thompson reportedly claimed that Lord Patten knew in 2011 that Mr Byford and another member of staff received settlements of more than they were contractually entitled to.
"In fact, Lord Patten was himself fully briefed, in writing as well as orally, about the Mark Byford and Sharon Baylay settlements soon after his arrival as chairman in 2011," Mr Thompson said.
Mark Thompson will appear before the Public Accounts Committee on Monday.