Iain Duncan Smith has warned British voters that "apathy" benefits extremists.

As fears grow that next Thursday's local election is set for a record low turnout, the Conservative leader cautioned the "stay at homes" that they could let fascists into power by the back door.

"No one can complain about who is running their councils for the next four years if they cannot be bothered to come out and vote," he told voters in north west London.

"It is the extremists who will turn out and benefit if people do not turn out. I say that people should come out and vote."

A Guardian ICM poll published on Tuesday indicates that as few as a quarter of voters will go to the polls on May 2 - with usually dutiful Conservative supporters as disengaged as anyone else.

Dire predictions of a poll collapse are fuelling fears that right wing extremists such as the BNP could clean up in race hotspots such Bradford, Oldham or London's East End.

During a visit to a Jewish secondary school in Hendon, north west London, Duncan Smith was presented with a 1,000 signature petition from pupils and staff condemning anti-Semitic attacks and calling on MPs to condemn inflammatory racist behaviour.

"The sort of extremism that creates this nightmare must be confronted," the Tory leaders said. "We and our neighbours must make sure that people like this are confronted - that hate is confronted."

Jean Marie Le Pen's gain in the French presidential election was a "wake-up call for politicians in Europe and across the board".

The collapse in support for centrist parties in France has sent a tremor through political establishments across Europe. Duncan Smith urged support for a mainstream "alternative" to extremism.

"They should be asking questions about why this has happened and why there has been a political vacuum which has allowed extremists to come forward.

"People must know that there is an alternative and the alternative is mainstream politics. I think in Britain, in the mainstream, that message is getting through," he said.