A man who disappeared after venturing into the Brisbane River on Sunday afternoon is still missing.

Search crews have not found any trace of a man who went missing in the Brisbane River more than 24 hours after he failed to resurface.

The man was with friends in Kookaburra Park at Karana Downs, southwest of Brisbane, when he was last seen going under the water.

Police and swift water rescue crews first attended about 2.15pm (AEST) on Sunday.

Some reports suggest the man was attempting to retrieve a ball when he vanished.

Two technical rescue firefighters assisted with the search on Monday using a specialised camera from a police boat, a Queensland Fire and Emergency Services spokeswoman said.

The search would continue into Monday night, a police spokeswoman told AAP.

Police have said there is no evidence to support suggestions the man was taken by a bull shark.