Election 2015: Peter Robinson to write to BBC and ITV

Mr Robinson said the DUP had more seats than the SNP, Plaid Cymru and Green parties

DUP leader Peter Robinson has said he will be writing to the BBC and ITV to find out why his party has not been included in those taking part in TV election debates.

It is understood broadcasters have put forward proposals that would include the SNP, Plaid Cymru and the Greens.

It comes after Prime Minister David Cameron refused to take part unless the Green Party was included.

Mr Robinson said the DUP had more seats than the SNP, Plaid Cymru and Greens.

Under the plans, the BBC and ITV would stage debates involving the Conservatives, Labour, Lib Dems, Greens, UKIP, SNP and Plaid Cymru.

Mr Robinson said the proposed leader debates were descending into farce, following the exclusion of his party from the process.

The DUP leader said the BBC and ITV would have to justify what he called a decision that lacked "logic and credibility".

Mr Robinson said he was angry that the fourth largest party at Westminster has been left out of the proposed format.

Northern Ireland he said, was being excluded from a national debate.

Sky and Channel 4's plans to host a head-to-head between Mr Cameron and Labour leader Ed Miliband remain unchanged.

The move comes after discussions between the broadcasters following a political row over the proposed format for the debates, to be held during the election campaign.

The initial proposals for the 2015 general election campaign included:

• a head-to-head between Mr Cameron and Labour leader Ed Miliband

• a three-way debate featuring Mr Cameron, Mr Miliband and Lib Dem leader Nick Clegg

• a debate between the leaders of the Conservative Party, Labour, Lib Dems and UKIP.

But Mr Cameron raised a number of objections to the proposals, principally that Green Party leader Natalie Bennett should feature.

The 2010 election had the UK's first prime ministerial TV debates

He said it was wrong to include UKIP leader Nigel Farage in one of the debates but not "other national parties".

This prompted Mr Clegg, Mr Miliband and Mr Farage to write to to the prime minister saying it would be "unacceptable" for him not to appear - and urging the broadcasters to press ahead without him.

A spokesperson for the broadcasters said: "The broadcasters remain committed to providing election debates in the run up to the general election. The debates played an important role in informing millions of our viewers in 2010 and we will continue to work with all the parties to ensure that they happen again in 2015."

Live prime ministerial debates featured for the first time in the UK at the 2010 election.

They proved popular with the British public, being watched by 22 million people.

The suggested schedule is for debates to be held on 2 April, 16 April and 30 April, ahead of the UK-wide poll on 7 May.