Vancouver police chief Jim Chu says he has fired a "rogue officer" for alleged offences that include selling marijuana. (CBC)

Vancouver police Chief Jim Chu says he has fired a constable on his force for allegedly using a police database illegally and selling marijuana both on- and off duty.

A two-month investigation involving 30 officers from both the Vancouver Police Department and the RCMP culminated Wednesday in the arrest of the constable and an alleged accomplice, Chu said.

"Just a few hours ago, we arrested one of our own, 31-year-old Constable Peter Hodson, and charged him along with his co-accused, Oscar Lapitan, with trafficking marijuana," Chu told a Vancouver news conference Wednesday afternoon.

Chu said Hodson is also facing more charges, including two counts of breach of trust and and one charge related to the illegal use of a police database.

In addition, he was charged with breaking and entering with the intent to commit extortion in connection with alleged street-level drug trafficking, Chu said.

All charges relate to alleged offences that occurred between Dec. 4, 2009 and April 20, 2010.

"I have taken the step of firing Hodson as of today," said Chu. "He is no longer a member of this department."

The chief said that what was uncovered during the investigation of Hodson "was disturbing and disgraceful."

"Investigators observed behaviour that suggested Hodson was trafficking street level amounts of marijuana both on and off duty," Chu said

The investigation suggested no conspiracy among other officers but "the actions of a single rogue officer," said Chu.

"I want to reassure the public that the integrity of the VPD, while shaken by this abhorrent incident, has not been broken."

Hodson is in custody and is expected to make a first court appearance Thursday.