The far-right British National Party has been accused of hijacking a royal event after its leader, Nick Griffin, said that he was going to attend a garden party hosted by the Queen at Buckingham Palace.

Although Mr Griffin was not invited directly, he said that he would accompany Richard Barnbrook, the BNP representative on the London Assembly, to the event in July. Antiracism campaigners, already alarmed at potential gains that the BNP might make as voters turn against the main parties, called on the Palace to rescind the invitations and described the situation as a “disgrace”.

Mr Griffin, who was convicted in 1998 of distributing material likely to incite racial hatred, told The Times that he would seek out the Queen to show her that “I am a human being and I do not have horns”.

He said that if he got the chance to speak to Her Majesty, he would inform her that ordinary Britons were fed up with multiculturalism and immigration, but added: “I imagine that they \ will try and herd Richard and I into some corner and make us talk to the corgies.”

Mr Barnbrook was invited by the Greater London Authority which received its annual allocation of 25 tickets. A spokesman for the GLA said that all assembly members were entitled to equal treatment regardless of their political background. He said: “It’s not for GLA officers to distinguish between people on the basis of their politics. That is what the democratic process is for.”

A Palace official said public bodies were allocated tickets each year and that the Royal Family had no influence over how they were distributed.

Claude Moraes, a Labour MEP for London, said that the event had been “cynically hijacked and manipulated by the BNP”.

Ged Grebby, chief executive of the campaign group Show Racism the Red Card, said the invitation was a “slap in the face for black Britons”. He added: “It gives credibility to an organisation that doesn’t deserve any.”

A spokesman for Searchlight, an anti-facist organisation that campaigns against the BNP, said that

Mr Griffin should have been barred from Buckingham Palace on the question of security risk alone.

Mr Griffin said his presence at the party was not a publicity stunt and he was looking forward to the experience. “It shows to people that the BNP may be controversial, but we are as much a part of the mainstream as anybody else.” Mr Barnbrook said: “I imagine there will be a to-do and a hoot. These things are going to happen.”

Boris Johnson, the Mayor of London, wrote to Darren Johnson, the chairman of the London Assembly, last night expressing concern about “potential embarrassment to Her Majesty”. He said that abuse of the invitation should not be tolerated and called on Mr Johnson to rescind it or require Mr Barnbrook to invite another guest. Boris Johnson said Mr Griffin’s presence threatened to turn a happy event into a political stunt.

This week Mr Barnbrook prompted further anger about the BNP’s increasing presence at high-profile events by attending the start of Britain’s campaign to host the 2018 World Cup football finals, at which Gordon Brown put an emphasis on diversity.

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