Liberal Democrat mayoral candidate Brian Paddick has slammed the latest congestion charge hike imposed by rival Ken Livingstone on the city's most polluting vehicles, arguing it will do little to ease congestion.

The congestion charge for drivers of 4 x 4 'gas-guzzling' vehicles in central London is to be raised from £8 to £25 per day from October, it was confirmed today.

Commenting on the mayor's initiative, Paddick cast doubt on the effectiveness of targeting higher polluting vehicles in cutting congestion.

"Those who can afford Chelsea tractors can afford a £25 ride into London," he said.

"Allowing small vehicles to enter the zone will only add to congestion and bring London to a halt."

Paddick, who last month pledged to put London's black cabs at the centre of his transport policies, claimed it was manufacturers who needed to be targeted in combating pollution.

""We should force manufacturers to meet new emissions targets and increase Vehicle Excise Duty for big polluters," he added.