The three planned televised general election debates will go ahead whether David Cameron wants to participate or not, the broadcasters have announced.
In a statement on Friday afternoon, the BBC, ITV, Sky and Channel 4 said they intended to press ahead with their previously announced plans for two debates featuring seven party leaders and one head-to-head between Cameron and Ed Miliband.
Earlier this week the prime minister issued what he said was a "final offer" on the debates. Downing Street said he was only prepared to take part in one 90-minute contest involving seven party leaders before 30 March.
Opposition parties including Labour accused Cameron of "arrogance" and said he was "running scared" of debating Miliband and the leaders of Ukip, the Lib Dems, the Greens, Plaid Cymru and the SNP.
And today the broadcasters hit back. "The broadcasters welcome the fact that the prime minister has for the first time agreed to take part in a televised debate. However, the group believes there needs to be two seven way debates of a minimum of two hours each, within the election campaign, allowing time to properly represent the views of all parties, covering a broad range of subjects," the statement read.
"The broadcasters also believe that a head to head debate between the two individuals who could become prime minister - David Cameron and Ed Miliband - is important - something the prime minister has publicly supported."
The broadcasters also made public a letter sent to Downing Street communications director Craig Oliver, in which they reject his demand that any debate or debates take place before the final month of the election campaign.
The letter says: "We believe that the formal election period is the right time to hold election debates. It is the point at which the parties have published their election manifestos and the point at which the electorate as a whole is most engaged with discussion of election issues and the public debate about the future of the country."
It adds: "We believe the proposal for just one debate of 90 minutes duration is insufficient to cover the main election issues with seven participants. Our 2 x 2 hour debates format will allow all seven leaders sufficient time to discuss properly a good range of the main election issues. One 90 minute debate with seven leaders would inevitably lead to much less ground being covered, with much shorter contributions from all involved.
"We very much hope that all invited leaders will participate in the broadcast debates. However, in the end all we can do -- as impartial public service broadcasters -- is to provide a fair forum for debates to take place. It will always remain the decision of individual leaders whether or not to take part.
"The debates will go ahead and we anticipate millions of viewers will find them valuable as they did in 2010. Our invitations will remain open to all the invited leaders right up to broadcast. We'll set no deadlines for final responses. We very much hope all the leaders will participate."