A press release issued by the port authority said masked protesters carrying bags containing "an unknown substance" trespassed onto Port Metro property at Canada Place at 10:15 a.m. Monday.
Rising Tide, an environmental activist group, posted a video of the encounter on YouTube, which shows a small number of people dressed as Santa Claus carrying sacks being pushed and grabbed at a building's entrance.
Rising Tide says the six Santas had lumps of coal in their sacks and were trying to deliver them to Port Metro Vancouver employees.
Coal expansion outcry
The group says it also wanted to read aloud comments from members of the public who are opposed to the expansion of coal shipping facilities that would turn the port into the largest coal exporter in North America.
The Fraser Surrey Docks proposal, which would move up to 8 million metric tonnes of coal off railcars and onto barges, for eventual shipping offshore, is accepting public input until the end of Tuesday, it notes.
In its statement, Port Metro Vancouver said the protesters allegedly attempted to access the operations centre, a restricted area subject to Transport Canada regulations, and a scuffle broke out.
"A number of our employees were physically assaulted and property was damaged during this aggressive act."
Rising Tide described the response from Port Metro staff as "disproportionately violent."
It said six police cars and a paddywagon showed up, and police held one of the Santas for questioning for 20 minutes before allowing her to leave.
The Vancouver Police Department told CBC News Monday night it is investigating the incident.
As of Monday night, no charges had been laid.