Labour targets Cameron by ridiculing shifts in Tory policies

He will be depicted as a computer-generated chameleon riding a mountain bike in a new party political broadcast designed to lampoon his policy shifts of recent months.

Mr Cameron will today launch the final phase of the Tories' local election campaign with the slogan "Vote Blue, Go Green", highlighting grassroots environmental initiatives by Conservative local authorities such as recycling and clearing up streets.

But Labour will mock his attempts to demonstrate that the Conservatives have reformed with an aggressive campaign aimed at highlighting Mr Cameron's shift in position since taking the leadership last year.

Labour's broadcast, to be screened tonight, will feature a cartoon "Dave the Chameleon", with helmet and bike, echoing his habit of cycling to work.

The broadcast, to be followed with press and billboard advertising and a campaign website, will show the cycling lizard over the slogan "available in any colour - as long as it is blue". No Labour politicians appear.

John Prescott, the Deputy Prime Minister who coined the "chameleon" tag, said: "This image shows exactly what David Cameron represents; a political chameleon who says whatever he thinks his audience wants to hear."

Party sources said the campaign was building on their claim that Mr Cameron had "flip-flopped" since he wrote the Conservatives' last general election manifesto. But they denieda negative personal campaign.

Mr Cameron will attempt to win the "green" vote for the Conservatives, using his local election launch to try to capitalise on the local environmental successes of Conservative councils. He will publish a document outlining the "green" policies of local councils and highlight their environmental plans for the future.

He will say that Conservative councils have the highest average recycling rates and claim they provide the cleanest streets.

Mr Cameron will again pledge to lead "a new green revolution in Britain" and invoke the environmental slogan "think globally and act locally".

He will say: "Conservative councils are bringing innovation and imagination to the challenges of tackling climate change at a local level. Conservatives are already the largest party in local government, and I'm encouraging our councillors to do everything they can to advance the green agenda."

Meanwhile, ministers attempted to play down the threat from the far right after a report by the Joseph Rowntree Charitable Trust suggested that support for the BNP was being fuelled by disillusionment with the major parties.

Phil Woolas, the Local Government minister, said the impact of the BNP was being felt only in a few parts of the country. Andy Burnham, a Home Office minister, warned not to give the party "undue prominence".

"They pose a very localised threat and I am worried that if we give them too much coverage, it can back up the notion that they are a potent protest vote."