The union representing bus drivers in the Lower Mainland is offering a $2000 reward for information after a female driver was sexually assaulted in East Vancouver.

The woman, who cannot be identified for legal reasons, was allegedly groped by a man on the No. 22 Knight Street bus route early on New Year's Day.

Don Macleod, President of the Canadian Auto Workers Local 111, says the union is appalled by the alleged assault.

"We have at least 150 assaults each year against our members out there, and in terms of sexual assaults against our female drivers, there have been four since 2009.

"It's a great concern to the union and our membership out there that work alone," said Macleod.

The Vancouver Police Department are investigating and are already examining onboard security camera video of the alleged incident.

Women make up about 12 per cent of the 3,600 bus drivers employed by The Coast Mountain Bus Company, a subsidiary of TransLink which runs the region's bus service.

The alleged sexual assault comes almost a year after Del Louie viciously assaulted bus driver Charles Dixon at Edmonds Station in Burnaby on Feb. 15, 2011.

MacLeod said bus drivers want to see a tough punishment including jail time for Louie, who is due to be sentenced on Feb. 7 this year.