A police officer has been charged with assault following an on-duty incident with a female taxi passenger a year ago.

Calgary Police announced the criminal charge on Thursday, just a week after revealing similar, but unrelated, charges against three other officers.

Police released few details about the incident, only saying it happened on Jan. 27, 2009.

The officer was on duty in the downtown area at about 2:30 a.m. when a taxi driver asked him to help with a "domestic situation" that was happening in the back of his cab.

Police said the officer had "an interaction" with a female passenger.

"We have a very junior police service out there now," said Al Redford, deputy police chief. "And we are asking our more junior people and most inexperienced people to go out there and do the toughest job the police service has, which is patrol – dealing with the public 365 days a year."

Redford said all incidents involving the use of force are taken seriously.

The matter was investigated internally and the findings were forwarded to the Crown lawyers' office in Edmonton, which recommended the assault charge.

"The member is currently assigned to an administrative position and will remain in that position, pending the completion of the criminal proceedings," police said in a press release.

The officer, who police won't name, has six years experience with the force.

"As this relates to an on-duty incident and the charge was laid as a result of the member's execution of his duties, his identity will not be released at this time."

Last week, Calgary police announced assault charges against three officers following altercations at traffic stops, with one incident involving a driver getting stunned by a Taser.

One incident involved two officers stopping a driver in December of 2008.

In the second case, an officer and a driver had a "physical altercation" in April. The officer used a stun gun on the driver. He has been charged with assault with a weapon and assault causing bodily harm.