BBC stands by BNP leader invitation

Mr Hain, a long-standing campaigner against apartheid, has written to BBC director general Mark Thompson warning he could face legal action if he allows Mr Griffin to take part in the flagship political show.

The Welsh Secretary argued that the BNP was currently "an unlawful body" after the party told a court last week it would amend its whites-only membership rules to meet discrimination legislation.

In a letter to Mr Hain, Mr Thompson responded: "According to the advice we have received, the British National Party is not prevented from continuing to operate on a day-to-day basis and its elected representatives continue to sit on councils and in the European Parliament.

"It remains the BBC's obligation to scrutinise and hold to account all elected representatives and to do so with due impartiality. We are also advised that if there were to be any election - local or national - tomorrow, the BNP would still be able to field candidates.

"We therefore do not agree that the developments in the Central London County Court proceedings legally inhibit the BBC from allowing Nick Griffin to participate on the Question Time programme and our position remains as set out."

Mr Griffin is due to appear on Thursday's edition of Question Time alongside Justice Secretary Jack Straw, representatives of the other main parties and black writer Bonnie Greer.

But in his letter, Mr Hain said that the invitation to the BNP leader should be suspended until he is able to agree a new constitution with his party that meets the requirements of anti-discrimination laws.

"If you do not review the decision you may run the very serious risk of legal challenge in addition to the moral objections that I make," he warned.

Anti-fascist campaigners plan to stage a protest against Mr Griffin's presence on the show at the BBC's Television Centre in west London when it is filmed on Thursday.