Ed Miliband has accused David Cameron of running away from the leaders debates after he refused to take part in any during the election campaign . David Cameron tonight flatly refused to appear in televised leaders debates during the election campaign - despite Britain's biggest broadcasters threatening to go ahead without him. Number 10 said the Prime Minister's position was 'clear' – reiterating that he was willing to do one seven-way debate at the end of March but no more. Downing Street's response came after the BBC, ITV, Sky and Channel 4 rejected his 'final offer' – and threatened to 'empty chair' him if he did not show up. They said they would stick to their plan for three debates during April - including a head-to-head showdown between Mr Cameron and Ed Miliband - and urged Mr Cameron to 'reconsider' his refusal to take part in these shows. Downing Street had written to the broadcasters on Wednesday saying the PM's 'final offer' was a single 90-minute debate featuring at least seven leaders before March 30. But in a joint statement, the broadcasters said they would stick to plans for a seven-way debate involving Mr Cameron, Labour's Ed Miliband, Nick Clegg of the Lib Dems and the leaders of the Greens, Ukip, Scottish National Party and Plaid Cymru on ITV on April 2. This would be followed by a second show on BBC featuring the same line-up on April 16 and a final one-on-one clash between the Tory and Labour leaders on Sky News and Channel 4 on April 30 - exactly a week before the May 7 election. In a letter to Mr Oliver, the broadcasters made clear they were ready to go ahead with the debates even if Mr Cameron decides not to take part - effectively 'empty-chairing' the Prime Minister. They wrote: '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.' Mr Clegg called on the Prime Minister to join the debates in a message on Twitter: 'Come on, David Cameron, you haven't got your own way so accept it and take part.' Labour leader Ed Miliband said the Prime Minister's was running scared of taking him on in leaders debates . The Deputy Prime Minister Nick Clegg said the Prime Minister should accept the broadcasters' decision . Scotland's First Minister Nicola Sturgeon said the BBC, ITV, Sky and Channel Four had called Mr Cameron's bluff . But Number 10 immediately hit back at the broadcasters tonight. Craig Oliver, Downing Street's director of communications, replied to the broadcasters: '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 March 23rd. '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. Best wishes, Craig Oliver.' The Prime Minster's Director of Communications Craig Oliver has written to the broadcasters tonight . The standoff leaves the prospect of election debates hanging by a thread. In their statement, the broadcasters said: 'Today the BBC, ITV, Channel 4 and Sky confirm they will continue with the series of televised leaders' debates as planned in the general election campaign. '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 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.' They added: 'The broadcasters would like the Prime Minister to reconsider taking part in all of these debates. Twenty-two million people watched the leaders' debates in 2010 and there is a public desire and expectation for them to happen again in 2015 . 'The broadcasters' proposals have come after extensive work over the last six months to ensure the public have the opportunity to watch televised election debates once more. 'The group have worked in an independent, impartial manner, treating invited parties on an equitable basis. They have listened to the views expressed by all parties and adapted the proposals to take into account electoral support. 'The broadcasters will continue to work closely with all parties invited to take part in the televised debates to bring them to their millions of viewers across the UK. The heads of news of all four broadcasters would welcome the opportunity to meet Mr Cameron, or his representatives, to discuss the debates.' Following stormy exchanges on the debates at Prime Minister's Questions in the Commons on Wednesday, Sky News and Channel 4 said they were ready to move the two-header debate to another date if Mr Cameron and Mr Miliband could agree on a preferred day. The new statement made clear that this offer remains on the table. Green Party leader Natalie Bennett and the SNP's Nicola Sturgeon have attacked the the Prime Minister's stance over the debates . In the letter to Mr Oliver, the broadcasters said elements of the debate he proposed had not been 'fully thought through'. They said his proposal involved 'an idea that you had not raised in the previous six months of discussions' on the debates. The letter said: 'We believe the proposal for just one debate of 90 minutes duration is insufficient to cover the main election issues with seven participants. 'Our two x two-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.' They added: 'We have given your proposal serious consideration but we don't think it achieves the goal of providing our viewers with election debates that can properly explore a reasonably full range of issues.' Nigel Farage has claimed the Prime Minister has set out from the start to ruin the leaders debates . In a sign that they will keep the door open for Mr Cameron to perform a last-minute U-turn, they said: '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.' Ukip leader Nigel Farage said he would 'accept the challenge' of taking part, even though he preferred the broadcasters' earlier proposal for a four-way debate featuring himself, Mr Cameron, Mr Miliband and Mr Clegg. He said: 'I'm pleased that the broadcasters have stood firm at last but it would have been far better had they stuck with their original proposal which included fewer parties. But nonetheless we accept the challenge.'
Number 10 said PM would do one seven-way debate at the end of March . But Cameron will not take part in any debates during the election campaign . Broadcasters said they planned to go ahead with three debates in April .