The Tories and Labour are engaged in a fresh row after broadcasters announced an agreement over televised election debates with David Cameron taking part in one with the seven main political leaders but no head-to-head with Labour's Ed Miliband.

Labour has now accused David Cameron of being a "coward". Cameron and Miliband will be interviewed and answer questions from a studio audience on a Sky News/Channel 4 programme on Thursday - but there will be no direct exchanges between the two. The 90-minute programme will be presented by Jeremy Paxman and Kay Burley.

Cameron, Miliband and Liberal Democrat leader Nick Clegg will also feature separately in a BBC Question Time special on April 30, just a week before the nation goes to the polls. The three leaders will answer questions separately from a studio audience.

A single seven-way debate with seven party leaders will take place on ITV on April 2, although verbal exchanges between the Miliband and Cameron are expected to be limited. Leaders from Labour, Conservatives, Liberal Democrats,the SNP, Greens, Plaid Cymru, and Ukip will take part.

On April 16, the five opposition party leaders will debate on the BBC. It will feature Miliband, UKIP's Nigel Farage, SNP leader Nicola Sturgeon, Natalie Bennett from the Greens and Plaid Cymru's Leanne Wood.

The BBC says it also will ensure "fair representation" of the Northern Ireland parties.

The final line-up follows long wrangling between parties and broadcasters. Cameron rejected previous proposals on the basis they did not include the Greens, and insisted the sessions should not take place during the short election campaign that starts on March 30.

Miliband said: "David Cameron is now in a ridiculous position where he is willing to go to the same studio as me, on the same night as me, face the same audience as me, but he won't debate me head-to-head because he is running scared.

"Now, I am going to keep the offer of a head-to-head debate with him on the table right up to election day, because I think it is what the British people want and the British deserve."

But a Tory source insisted they had secured an even better deal than they were hoping for.

"The PM has always believed too many debates would suck the life out of the campaign," they said.

"In all these formats, we are confident the choice between competence and chaos will be clear."

Sturgeon said: "The SNP have always said that we will take part in General Election debates anytime and anywhere, and look forward to doing so. We have an attractive message to stand up for Scotland's interests at Westminster, and I believe that this positive case will prevail in election debates.

"Our preference would have been for broadcasters to stick to their original proposals, and not be pushed around by the Westminster parties, particularly the Tories. However, it is good that the debate about the debates is finally over and we can get on to discussing the real issues of substance."