THE BBC Trust today rejected a complaint by Scottish and Welsh nationalists over a decision which excludes them from taking part in a national TV leadership debate.

SNP and Plaid Cymru politicians had lobbied for their leaders to take the podium alongside Gordon Brown, David Cameron and Nick Clegg in the third debate next Thursday.

They argued that, because the BBC is a public service broadcaster and funded by the licence fee, the leaders of the devolved nations should also have their say.

But the BBC Trust rejected the appeal today after meetings and correspondence between the parties and BBC representatives during the last month.

SNP leader Alex Salmond said: "The exclusion of the SNP and Plaid Cymru, parties of Government in Scotland and Wales, from the election leaders' debates is a democratic disgrace.

"Today's decision shows that the BBC has given up all pretence of being a national broadcaster for Scotland.

"Fairness and impartiality have been thrown out of the window in what amounts to blatant discrimination against both parties and both countries.

"The corporation has jettisoned more than 80 years of impartiality for the electoral convenience of the London-based parties.’’ Liberal Democrat UK leader Nick Clegg's strong performance in the first televised debate, broadcast from Manchester by ITV last Thursday, has improved the party's standing in the polls.

The topic of tonight's debate, which is being broadcast by Sky from Bristol, is foreign affairs.

Mr Salmond said: "There can no longer be any question that the leaders' debates are dominating the election campaign, but licence fee-payers' in Scotland and Wales are being short-changed as the result of an undemocratic carve-up which cuts both nations out of the picture.

"With today's decision, the BBC has proved it is part of the same discredited establishment machine as the Westminster parties which the electorate are raging against.’’ Both the SNP and Plaid Cymru are reviewing their broadcasting policy - which has historically supported the continuation of the BBC licence fee.