A crackdown on Beijing's black taxis - private vehicles illegally carrying passengers for money - kicked off on Monday in a bid to stop the disarray in public transportation and improve the capital's traffic system.

The crackdown, which will last until the end of the year, will concentrate on getting black taxis and three-wheeled motorcycles off the roads.

Wang Xin, a press officer from the Beijing public security administration, said the crackdown involves the police, the traffic control department, and industry and commerce administrators.