OAKLAND -- Police Chief Howard Jordan has opened an investigation into the circumstances surrounding two officers filmed making repeated visits to a downtown Oakland karaoke bar that nearby residents suspect might double as a brothel.

"I take these allegations very seriously, and the department opened investigations as soon as the circumstances were brought to my attention," Jordan said in a prepared statement.

The manager of Cafe Juliet, the establishment in question, insisted Monday that there was no sexual activity taking place and that the officers were merely performing security checks to make sure people in private karaoke rooms weren't doing drugs.

"The accusation is total bull (expletive)," the manager, John Chang, said.

KTVU staked out Cafe Juliet several nights recently after learning that a Port of Oakland official had spent public funds there. The port is facing increased scrutiny after revelations earlier this month that one of its executives had sought reimbursement for entertaining business associates at a Houston strip club.

KTVU's cameras recorded "women in skimpy clothing" filing into the business at 266 14th St., four blocks from City Hall. The station also recorded two uniformed officers, Sgt. Warren Young and Officer Barry Ko, making repeated visits there.

Chang said the women filmed were both waitresses and customers of the bar, which serves mostly Chinese patrons.

Police did receive one anonymous tip two years ago about prostitution possibly occurring at the karaoke bar, according to Sgt. Chris Bolton. However, over the past three years, police received only three calls for service at the establishment, none of which were linked to criminal activity.

Department regulations do allow officers to make security checks at businesses. Officers also are allowed to take lunch breaks at restaurants, although they can't sit at a restaurant's bar.

Neither officer identified in the videos has been placed on leave during the investigation, police spokeswoman Johnna Watson said.

KTVU filmed Sgt. Young enter the establishment the first night it began filming.

The second night, it filmed Ko make two visits, including one that lasted 27 minutes, and Young make multiple visits.

When a KTVU reporter asked Young about his visits, the sergeant said he had a friend working at the karaoke bar. Pressed further, he said that he performs a security check there and that the bar is not home to prostitution.

Contact Matthew Artz at 510-208-6435.