An air, water and land search and rescue operation for a 34-year-old man reported missing after falling into the Brisbane River will resume in the morning.

Friends saw Mr Jarvis by the water and he disappeared a short time later. ( Supplied: Queensland Police Service )

Police suspended the search for the Toowoomba man, identified as Matt Jarvis, who was reported missing around 7:45pm on Saturday night in the vicinity of Lower River Terrace at the bottom of Kangaroo Point cliffs.

Acting Inspector Teena Rolls said Mr Jarvis was at the barbecue area of the cliffs when he walked off from the group he was with towards the water's edge.

"He was with a friend at the time, who's turned her back and then she has heard a splash, a rustling of the trees, and then she's called out that she thinks it was Matt who was in the water," Acting Inspector Rolls said.

"The group's gone to the water and had seen splashing, and they've entered the water in a bid to locate the missing person but were unable to locate him at that time."

Volunteer marine rescue boats help in search for the man. ( ABC News: Lexy Hamilton-Smith )

She said other witnesses saw a man in the water who had gone under, and was not seen again.

Police said the group had been socialising and drinking by the river.

Mr Jarvis is described as Caucasian, approximately 170 centimetres tall with a proportionate build, fair complexion and long brown dreadlocks.

He was last seen wearing a white long-sleeve shirt with black dots, dark green cargo pants, light coloured cap and Nike shoes.

Water police scour the Brisbane River for any signs of the man. ( ABC News: Lexy Hamilton-Smith )

Police divers, swift water rescue boats, Volunteer Marine Rescue and PolAir had searched the area.

On Sunday, police set up a command post by the river and were conducting a line search of the banks, while Rescue 500 is searching from the air.

Police have notified the man's next of kin and are making enquiries to ensure the man has not exited the water at some point.

Anyone who may have witnessed the incident or has any other relevant information is urged to contact police.