Downing Street has accused Jeremy Corbyn of "running scared" of a Brexit TV showdown with Theresa May amid continued wrangling between the two sides over the format.
No 10 confirmed there is still no agreement on the debate, due to be screened on Sunday December 9 - two days before the crunch Commons vote on the Prime Minister's Brexit deal.
The latest spat erupted after Mr Corbyn said on Saturday he was prepared to accept Downing Street's preferred option of the BBC, provided it was a straight head-to-head discussion between the two leaders. The Labour leader had previously indicated his support for a ITV proposal based on a simple one-on-one format, in contrast to the BBC offer which also involves the leaders taking questions from a wider panel.
But Labour hit back, arguing it is the Prime Minister who is trying to avoid the confrontation.
"As she did during the general election campaign, Theresa May is running away from the scrutiny of a real head-to-head debate with Jeremy Corbyn," a spokesman said.
"Why else would she not accept ITV's offer of a straightforward head-to-head debate, as Jeremy has done?
"Instead, her team are playing games and prefer the BBC's offer, which would provide less debating time and risk a confusing mish-mash for the viewing public."
Meanwhile, Liberal Democrat leader Sir Vince Cable has complained the proposal for a debate between the Conservative and Labour leaders - both of whom support Brexit - meant other views are excluded.
In a letter to the BBC, ITV and Sky, Sir Vince put himself forward as an advocate for a so-called people's vote in a second referendum.
"The principal alternative to the Withdrawal Agreement is for the UK to remain as a full and influential member of the European Union," he said.
"All the evidence suggests that there is now a majority in the country for doing so, and a substantial majority for a people's vote. Yet neither Jeremy Corbyn nor Theresa May supports this route."