Three general election TV debates are set to go ahead despite the ongoing row over David Cameron's refusal to take part in two of them.

The BBC, ITV, Channel 4 and Sky News have agreed to broadcast the debates in April and said they would be prepared to "empty-chair" the prime minister if he failed to turn up.

The broadcasters urged Cameron to reconsider his position to take part in only one 90-minute-long debate, featuring the leaders of seven political parties, claiming there was "still room for negotiation".

The debates will take place on 2, 16 and 30 April, with two of them scheduled to include a head-to-head debate between Cameron and Labour leader Ed Miliband.

Previously, Labour accused the prime minister of "running scared", while Liberal Democrat leader Nick Clegg said he was prepared to stand in for Cameron in a tete-a-tete with Miliband.

In a response to the broadcasters, Cameron's spokesman Craig Oliver said: "I made the Prime Minister's final position clear in my last letter - he is willing to do a seven-way debate in the week beginning 23 March.

"Clearly it is disappointing that you are not prepared to take him up on that offer. I am ready to discuss at your convenience the logistics of making the debate we have suggested happen."