Qantas says an "inappropriate message" written on the side of a bag caused this afternoon's delays at the Brisbane Domestic Airport.

A Qantas security official says ramp staff raised concerns when they found a bag with the word 'bomb' written on it, but the bag was later deemed not to be a risk.

The matter has been referred to police.

Greg Anderson arrived on a flight from Cairns this afternoon and says passengers were kept waiting for more than an hour.

"When we came off the plane, the carousel with the baggage stopped and originally I went up and spoke to the baggage people - they said they weren't sure what was going on," he said.

"Then about 10 minutes later, it came over the loud speaker that there was congestion at the airport and that was the reason.

"Then probably another 15 minutes after that, they said it was a security scare."