Main parties accused of failing to confront the BNP

An all-party campaign against the British National Party has accused Labour, the Conservatives and Liberal Democrats of boosting the BNP's general election prospects by not tackling the party head-on.

In an interview with The Independent, James Bethell, director of the Nothing British group, warned that Gordon Brown, David Cameron and Nick Clegg were adopting hopelessly out-of-date tactics and failing to address the legitimate grievances of alienated white working-class voters.

Mr Brown called the BNP a "nasty extreme party", Mr Cameron labelled it a "ghastly piece of filth" and Mr Clegg said it was made up of "fascist thugs". But Mr Bethell said mainstream parties should be more open about policy issues such as immigration to address the anger of up to five million people. He warned that the BNP had "struck a nerve" among people with "no hope" and could become a permanent force in British politics, with a potential 12 per cent share of the vote.

The BNP will field a record number of general election candidates on 6 May – possibly more than 300. Nothing British is sending a guide to the other candidates in constituencies where the right-wing party is standing. It warns that the BNP is modernising, has shelved talk of forced repatriation and is as likely to campaign against the war in Afghanistan as immigration. It is choosing presentable candidates including more women, and screaming "fascists" at the party is as likely to annoy the public as persuade them, says the guide.

Mr Bethell, a Conservative who was managing director of the Ministry of Sound nightclub, said: "The mainstream parties must have the guts to confront toxic issues – immigration, national identity, Islamism and the divided nature of our society."

He argued that traditional attacks on the BNP would not work because they did not accord with people's experience of the party. Its members now wore suits and fluorescent jackets and took part in social action projects such as building a scout hut, clearing snow and even removing racist graffiti.

Mainstream parties have often sought to deny the BNP the "oxygen of publicity" – refusing to share a platform with it or addressing its policies directly. But Mr Bethell said: "In the old world of a handful of newspapers and the BBC, it was possible to keep the BNP out of the headlines. Those days are over. It doesn't need the national media. It operates below the radar using 'guerrilla marketing', and has a strong online presence. People turning to its politics have bona fide grievances.

"The people thinking of voting for it will have been hardest hit by globalisation, which has been good for the better off but an unmitigated disaster for those whose jobs have moved somewhere else. Politicians need to stop sitting on their hands and get stuck in."

Mr Bethell praised Mr Cameron for taking social issues seriously but said he had been "overly cautious in confronting the extremism and racism of the far right". Anti-BNP campaigners think Tories with northern roots such as party chairman Eric Pickles have taken a more proactive stance against the BNP than the "Notting Hill" set around Mr Cameron, who favour a low-key approach to immigration after the Tories were branded "the nasty party" for raising it during the 2005 election.

"The [Tories'] missing component is not necessarily policies. It is empathy and being prepared to engage with people who are angry and frustrated," said Mr Bethell.

Yesterday senior BNP figures met after the sacking of the party's publicity chief Mark Collett, who was arrested on suspicion of threatening to kill its leader Nick Griffin.