Mike Russell, the Scottish Culture Minister, said of the decision to invite MEP Nick Griffin, the BNP leader, on to the flagship show tonight: “BBC managers in London must explain why they are bending over backwards to accommodate this overtly racist party, which has absolutely no standing north of the Border.”

He added that the BNP was “virtually invisible in Scotland, yet Scottish viewers will be inflicted with their spiteful and hateful message on a flagship programme on our national broadcaster”.

A specially convened BBC Trust panel met last night and confirmed that Mr Griffin will be allowed on to Question Time, saying that it was “a question of editorial judgment” whether it was appropriate for the BNP to be represented on the flagship show.

At a rally in central London pop stars, writers and union members condemned the BBC for giving the BNP a platform on the programme. Jerry Dammers, founder of the group The Specials attacked the BBC as naive for giving Griffin a chance to express his views. His words were echoed by the former children’s laureate Michael Rosen who said people had a right not to hear the BNP’s message.

The decision to have Mr Griffin on the programme was based on the party’s success in the European elections in June, when it won more than 940,000 votes and two seats. “We absolutely stand by that judgment,” said Ric Bailey, the BBC’s chief political adviser.

Security at Television Centre in west London will be tight as Mr Griffin, 50, makes his appearance alongside Jack Straw, the Justice Secretary, among others.

Anti-fascist activists will picket the building all day and step up their demonstration ahead of the filming of the programme in the evening.

A BNP spokesman made clear the party would not rely on police help to get Mr Griffin safely inside the building. “We will sort our own security out,” he said.

Reports have claimed the corporation has made emergency plans to move Question Time to another venue should the protests turn violent.

The programme will be recorded live at around 7pm with the broadcast at 10.30pm, giving managers time to edit out any questionable references or incidents.

Corporation chiefs insist the audience for the show has been put together in the normal way, but it has been disclosed that some BNP members will be in the audience.

Meanwhile, at Westminster, a decision to withdraw MEPs’ passes allowing them access to the Commons – a perk given in 1989 – was condemned as “absolutely scandalous” by Struan Stevenson, the Scottish Tory MEP.

Harriet Harman, the Commons Leader, said the decision was made because of pressure on parliamentary facilities. However, the move is thought by many to be directly targeted at the BNP.

Mr Stevenson denounced it as an over-reaction, saying the move to ban the two BNP MEPs would seriously disadvantage the 70 others in representing their constituents.

He said: “This is absolutely scandalous. It’s not just a hammer to crack a nut, the whole situation is absurd and they really need to think again.”