A far-right activist linked to the murder of Chris Hani, a prominent ANC activist, is just one of a number of white South Africans who are helping the British National Party as it gears up for the European elections.

Arthur Kemp was arrested in connection with the 1993 murder of Hani – one of the most popular black politicians in South Africa – which was intended to derail the country's transition to democracy. Although questioned, he was released without charge and came to the UK in 1996.

Now the editor of the BNP's website and the author of white supremacist books, including the March of the Titans: A History of the White Race, and The Lie of Apartheid, which includes an essay on the Hani murder, he was spotted in the BNP's election headquarters in Wales preparing thousands of campaign leaflets.

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According to the anti-racism magazine Searchlight, however, the largest traffic to the BNP's website comes from South Africa and it claims the party is targeting wealthy white South Africans for donations. "Many of them may be friends and relations of the growing number of South African BNP members, of whom Arthur Kemp, editor of the BNP website and in charge of the ideological training of the party's 250 or so elite activists, is the most prominent," Searchlight's website says.

A spokesman for the BNP said that Mr Kemp was a "valued member" of the party, but did not have a specific role in the election campaign. Yesterday, a spokesman for Searchlight said that Mr Kemp's involvement with the party meant that its attempt to present an acceptable public face and to move away from its controversial previous history of links to violent extremists was "unravelling".