The leaders of Plaid and the SNP question the BBC's debate decision
The BBC Trust has not upheld a complaint by Scottish and Welsh nationalists over their exclusion from the BBC's TV prime ministerial debate.
The SNP and Plaid Cymru wanted their leaders to be included in the three live TV clashes between Gordon Brown, David Cameron and Nick Clegg.
The BBC Trust said it was "appropriate" to exclude the SNP's Alex Salmond and Plaid's Ieuan Wyn Jones.
Mr Salmond said the BBC's decision was "a democratic disgrace".
"Today's decision shows that the BBC has given up all pretence of being a national broadcaster for Scotland, he added.
"Fairness and impartiality have been thrown out of the window in what amounts to blatant discrimination against both parties and both countries."
Plaid's director of elections, Helen Mary Jones, said it was "astonishing" that the BBC Trust had not allowed either it or the SNP to put their case across in person.
"Having shown complete disregard for Plaid and the democratic process of our nation the BBC can no longer claim to be a national broadcaster for Wales," she added.
The BBC will be hosting the last of the three live TV debates on Thursday, 29 April. ITV held the first last week, while Sky is organising the second one, which will be broadcast this evening.
Mr Salmond and Mr Jones will not be appearing in any of the shows.
The SNP said they are unlikely to take legal action against the BBC because they cannot afford it.
Mr Salmond claims it would cost £70,000, money that he says the party does not currently have in its coffers.
The BBC Trust said in a statement that the decision of the BBC's Director General to exclude the SNP and Plaid Cymru from the third debate was "appropriate" regarding impartiality.
It added that the SNP and Plaid leaders would instead be taking place in televised debates in Scotland and Wales respectively, and that these were being "clearly signposted" by the BBC.
The BBC has long maintained that only the Labour, Lib Dem and Conservative leaders are being included in the main televised debates, as they are the only three people who could go on to become the next prime minister.