Douglas Alexander has defended the government's road pricing plans and said that organisers of an online petition against the proposals were spreading "myths". 

The transport secretary said the email encouraging people to sign up contained "a number of fictions" and pledged to press ahead with plans to pilot the scheme.

More than 1.1 million people have joined the campaign objecting to proposals for national congestion charges as "sinister and wrong".

They oppose installing electronic tracking devices in cars to follow their movements and to increases in road taxes.

Alexander played down the significance of the campaign, saying it was "just one contribution to the debate".

He said he expected similar-sized petitions in favour of the scheme to come in the future.

But he said the scheme would be scrapped unless it attracted public support.

He told the BBC: "We've got a big response to this petition. I imagine there will be other petitions in the future with equally large responses, but it's an important part of the debate that we want to see."

Speaking on Radio 4's Today programme, he said: "If you look at the petition itself, there are a number of myths which have been perpetrated and that's why I welcome the opportunity to set some of the facts straight.

"It's no doubt that those people who initiated the petition had a particular point of view in mind.

"I think it's perfectly fair that people express an opinion. Ultimately the job of Government is to try and reconcile what are often competing, even contradictory, opinions held by the public.

"We need to recognise in this country that we don't have a choice but to deal with the growing problem of congestion."

Downing Street

Number 10 said it was pleased there was a "lively political debate" about the subject.

The prime minister's official spokesman told reporters: "But the debate in itself doesn't produce a solution. The crucial point about this issue is that doing nothing isn't an option."

"This isn't us stepping immediately to a national pricing scheme, it is about setting up pilot schemes to find out the facts, and then learn the experience of that and then decide where we go."

He said the government would recognise the strength of feeling indicated by the size of the petition, but said "it's not a matter of numbers".