Twenty-one of London's 33 boroughs were also taking part, according to Richard Evans, in charge of Britain's contribution to the initiative, expected to see some 1,000 communities around Europe leave their cars at home for the day.

"In central London, a number of streets around the British Museum will be closed, and one of them, Museum Street, will remain closed for the next six months," Evans told AFP.

In northwest England, Liverpool closed streets in the city centre for the day and neighbouring Manchester closed off its main square in the centre of town.

Scotland also took part with Glasgow closing off parts of its city centre to traffic on Sunday to coincide with a local festival.

A bus company in Hereford, central England, tempted motorists out of their cars by offering city-wide travel for the day for just 1 pound (1,43 euros, 1,64 dollars).

According to a commission, partly sponsored by the government, Britain has the most congested roads and the longest commuting times in Europe.

People in the Britain also make more use of cars than any other European country, despite having below average car ownership.

In February drivers in central London were hit by a congestion charge which Evans said had been "successful beyond expectation".

The city is one of the first capitals in the world to impose such a road tax which stands at five pounds (7,5 euros, 8,22 dollars) and applies to motorists entering a zone in central London during working hours.

Figures released in June showed the congestion charge had reduced the number of traffic jams in central London by 40 percent, and the number of private cars on roads in the zone by 16 percent.

The system relies on a network of more than 800 roadside cameras, which take close-up pictures of vehicle license plates. These are sent to a central computer, which can check whether the charge has been paid.

Tens of millions of Europeans were set for a breather from heatwave-related pollution on Monday.

"Car-free days" were first introduced in France in 1998 to enhance awareness of pollution from motor vehicles. The event is also an opportunity for real-life tests of some alternatives as traffic is barred to entire urban areas.

TERRA.WIRE