Sac jackings" occur when motorists are stuck in a jam. Thieves smash the car window and run off with a handbag from the passenger's seat.
In 2006 only 128 incidents were reported to the police. Last year the figure surged to 359.
The figures are published in today's edition of the daily Het Laatste Nieuws.
The police say figures for 2008 will be lower, but in the police zone City of Brussels/Elsene 287 cases have been reported since January.
During the last two months 30 thieves were caught red handed.