West Midlands drivers are being offered free public transport if they forego their car as part of an international green campaign.

The region's public transport executive Centro is calling on people to support "In Town Without My Car Day" later this month with the offer of free travel cards - which can be used on buses, local trains and metro trams - on September 22.

"This campaign day is an ideal opportunity for anyone who wants to do their bit to cut congestion and help the environment - and if they are persuaded to give up their car on a regular basis that would be even better," said Rachel Hooper, regional officer for TravelWise, the organisation co-ordinating the event.

The car-free day was launched by the rollerskating train stars of Andrew Lloyd-Webber's smash musical Starlight Express, performing at the Birmingham Hippodrome.

To take advantage of the campaign, motorists need to pledge to leave their car at home on the day and, in return for completing a pledge form via the Centro website - www.centro.org.uk - they will be sent a one-day Centrocard.

Previous Centro schemes to cut car congestion include offering discounted travel passes via major employers, which is calculated to save two million car journeys a year, and the offer of free park and ride at rail and metro stations, which now takes more than 2.5 million trips a year off the region's roads.

"Traffic congestion is a major source of frustration," said Councillor Roger Horton, of the West Midlands Passenger Transport Authority. "It also costs the West Midlands economy money and adds to pollution."