Broadcasters today said general election TV debates will go ahead with party leaders who accept, effectively threatening to "empty chair" any who decline to take part.

In a joint statement, the four major broadcasters confirmed plans for a 7-7-2 format, under which two debates hosted by BBC and ITV would feature the leaders of Conservatives, Labour, Liberal Democrats, Ukip, the Greens, Scottish National Party and Plaid Cymru, and a third on Channel 4 and Sky would pit David Cameron against Ed Miliband in a head-to-head clash of the two men most likely to emerge as prime minister.

The broadcasters said that if any of the leaders decide not to participate, "the debates would take place with those who accepted the invitation".

Proposed dates for the debates are April 2, 16 and 30 - with the final clash coming exactly a week ahead of the May 7 poll.