Campaign group Unite Against Fascism threatened to disrupt the proceedings planned for Liverpool yesterday evening after one of the candidates, Peter Phillips, admitted he was a BNP member last Thursday.
Phillips is standing against Sunand Prasad and Valerie Owen in a three-horse race.
Although Phillips' admission was greeted by a chorus of disapproval, the single practitioner has refused to pull out of the race.
Due to the protest threat, RIBA bosses called off the debate 'in the interests of safety and security'.
RIBA chief executive Richard Hastilow said he was saddened the hustings would not go ahead. 'I am disappointed that this debate has been cancelled but we must take this precaution to safeguard our staff, members and guests,' he said.
'I emphasise that the BNP manifesto is directly contrary to the RIBA's formally approved Equal Opportunities Policy which values the contribution to architecture and society by people of diverse origins and backgrounds,' he added.
For more analysis of Phillips' tilt at the presidency, see today's AJ (AJ 22.06.06).