B.C's Coast Mountain Bus Company has been flooded with calls of support for a driver under investigation, after video footage captured him retaliating against an unruly panhandler.

"We've had a number of people call us, mainly through our customer information line, and a lot of it is in support of our operator," said company spokesperson Doug McDonald.

The driver has 28 years of experience and the company said he is embarrassed by the incident. On Friday, he was allegedly spat on and lost his temper.

The passenger accused of instigating the confrontation is a known panhandler, with a reputation for aggressive behaviour.

"This guy, he can push your buttons," said downtown resident David Smith.

CTV British Columbia tracked down the panhandler at the Coal Harbour seawall, and asked why he started the confrontation.

The panhandler said he had a valid fare, and that none of his spit hit the driver so he should not be accused of assault.

"I spat, and the spit landed on the floor and the change box," he said.

A video camera caught the driver chasing after the panhandler as he tried to board another bus and spitting back at him.

"Hey! F----head here doesn't ride. He f---ing spit on me," the driver can be heard saying. "You're not f----ing riding buddy, get off."

Footage then shows the driver walking back to his own bus, and telling others waiting at the station: "Anybody else want to f---ing spit on a bus driver?"

The panhandler said it was "logical" for the driver to retaliate and that he should not be fired for his actions.

According to the drivers' union, roughly a third of reported abuse against bus operators involves spitting, while some incidents have been far more violent.

Last year, a 64-year-old driver was kicked in the face by an angry commuter and required stitches in his eye.

Canadian Autoworkers Union Local 111 vice-president Jim Houlahan said he would be meeting on Thursday with the employer and the driver, who is currently on leave.

"I've had early indications from the employer that they're not looking to be heavily punitive here," Houlahan told CTV's Canada AM.

"They recognize that that's not going to be constructive or help anybody."

With a report from CTV British Columbia's Rob Brown