The Conservatives' official spokeswoman on London's congestion charge appeared to back civil disobedience yesterday, telling a packed public meeting it would serve the mayor right if motorists refused to pay the £5-a-day fee.

Angie Bray, the London Assembly member who speaks for her party on the scheme, was accused last night of "irresponsible" behaviour when she suggested to a public meeting that a mass boycott could scupper the charge.

Addressing more than 300 opponents of the charge at the Palace Theatre in the West End, Ms Bray said: "I can detect a growing mood for civil disobedience."

She invoked mayor Ken Livingstone's refusal to pay the poll tax during the early 1990s, continuing: "'Can't pay, won't pay', I suspect, is a slogan that is going to come back into use. It will serve Mr Livingstone right to have to stand on the other side of the barricades this time."

Ms Bray was speaking alongside Samantha Bond, the actor best know for playing Miss Moneypenny to Pierce Brosnan's James Bond, at a meeting convened to raise money for a last-ditch legal challenge intended to delay the scheme. Her remarks received a rapturous reception. One onlooker shouted: "Don't pay. Tell everybody you know not to pay."

Another suggested that motorists should boycott every shop and petrol station selling congestion charging tickets.

After the meeting, Ms Bray denied she was encouraging law-breaking, saying she personally planned to pay the charge. But her remarks came under attack from congestion charging enthusiasts.

Julia Lalla-Maharajh, director of transport at the business lobbying group London First, said: "We must give congestion charging a chance."

Lawyers challenging the scheme yesterday urged motorists to donate £5 - one day's charge - to a fighting fund to sue Mr Livingstone. The court case is backed by several West End stars, who say theatre staff need to drive to work because it is too dangerous to catch public transport home after shows finish.

Stephen Alexander of the law firm Class Law said the case would centre on whether the mayor had consulted the public adequately. He wants to raise £500,000 for the case. Mr Alexander claims that, for someone driving to work who earns £15,000 a year, the charge means an 11% drop in income and a 40% increase in tax.

The mayor's office brushed aside the court case yesterday, saying it was "simply reviving old arguments" put forward in an unsuccessful challenge by Westminster council last year.

London's congestion charge begins on February 17.