Police are searching for a gunman who robbed a tavern north of Brisbane after threatening a staff member.

The man entered the tavern on Nudgee Road, Banyo about 11.40pm on Tuesday night and demanded cash from the attendant.

The gunman then fled the scene with the money.

A police spokeswoman said there were three people in the hotel when the hold-up occurred.

The gunman had his face covered and was wearing dark clothing.

Meanwhile in a separate incident, police are investigating an attempted break-in at Ipswich.

Four men approached a service station on Warwick Road and one hurled a rock at the door when the attendant refused to open it. The men were last seen running down Turley Street.

Anyone with information about the incidents should call Crime Stoppers on 1800 333 000.