Motorists who illegally use bus lanes face being slapped with an on-the-spot fine from this week.

The annual campaign by Metro, the police and Bradford Council will continue throughout Christmas and the New Year until mid January.

The lanes, which can also be used by taxis and cyclists, are designed to improve the flow of buses, which can be carrying the same number of people as 30 or more cars, and enable them to skip congested stretches of the road.

Inconsiderate car drivers who block these lanes can cancel out the advantages they provide, say transport chiefs.

"By blocking bus lanes and parking in bus stop lay-bys, selfish motorists are making journey times longer for buses, hampering level-access boarding which so many passengers find useful and compromising the safety of all road users," said Metro chairman Councillor Ryk Downes.

"This annual campaign, with its prosecutions and fixed penalty tickets, costs some thoughtless motorists dear but it also acts as a clear reminder that the restrictions which are in place to improve our public transport system apply to all drivers."

This is the fourth year that Metro and its partners have run this scheme.

Last year nearly 1,900 offences were detected, which also included people who were driving while disqualified or without insurance.

And more than 100 tickets were issued to drivers in only four hours during two separate crackdowns in Manningham Lane last January.

Inspector Ron Jones, of West Yorkshire Police, said: "This is just one of a number of campaigns in the region aiming to increase awareness about safe and lawful driving.

"People who ignore traffic laws and make driving inconvenient, even hazardous, for other road users can cause accidents that could lead to people being seriously injured, if not killed as a result.

"While the majority of drivers obey parking and bus lane restrictions, the minority who don't should be aware that we will take action where necessary in the form of prosecutions and fixed penalty notices.

"At this time of year, the weather and increased traffic in city centres can also make driving more hazardous, so it is even more important for this reason that drivers think about how their actions could affect others.

"As previous years' campaigns have shown, we are prepared to take the necessary action to reduce incidents of this kind and to reinforce the message to all drivers."

Councillor Anne Hawkesworth, the Council's executive member for environment and culture, said the lanes were allocated for a reason.

"In order for bus lanes to work to their potential, drivers must stick to the rules."