Wardens in seven boroughs - Croydon, Hammersmith, Haringey, Hounslow, Islington, Merton and Tower Hamlets - are taking part.

The strike is part of a campaign for the London weighting allowance to be increased to £4,000 a year.

The Unison union said the action would cost local authorities thousands of pounds because parking tickets would not be issued.

'Parking as usual'

"We are going to start hitting London councils where it hurts - in the pocket and in the high-profile services that no one can ignore," said London convenor Geoff Martin.

However, motorists have been warned the strike is not a green light to park anywhere.

The Association of London Government (ALG) said police wardens would not be involved in the action, and it would be "parking as usual" in the capital during the week.

"The strike only covers seven boroughs and they have plans in place to make sure there is a skeleton service operating," said a spokeswoman.

Series of strikes

ALG said councils simply could not afford to meet the union claim, which they estimate would cost them about £250m.

Further strikes will be held later this month by finance workers, street cleaners and environmental health officers as part of a union demand for increases in the allowance, which currently ranges from about £1,700 to £2,400 a year.

Thousands of council workers in the capital have staged a series of London-wide strikes in support of the pay claim.

The latest came last week, when schools, housing benefit offices, libraries and refuse collections were affected.