The Anti-Nazi League, which is planning to lead protests outside the counts in every area where the BNP is fielding mayoral or council candidates, said the authorities should have been ready for anything.
A spokeswoman said: 'BNP candidates have convictions for violence and attacking people. We should be aware of that.'
She said when the BNP won its last seat in a London by-election in 1993, the vote was marred by violence.
But many councils and police forces made little provision to deal with potential trouble. Even councils with multiple BNP candidates such as Bexley LBC, which had seven, Oldham MBC, five, and Gateshead Council, three, did not make arrangements.