'Drunken stunt': British tourist vanishes after jumping off bridge into Brisbane River

Fears are growing for a British backpacker still missing after taking a running jump into the Brisbane River in what police have described as a 'drunken stunt'.

The 30-year-old was the first of four friends who planned to jump from the William Jolly Bridge in Brisbane's CBD around 10.30pm on Sunday, police say.

His friends told police that they watched him disappear under the water and then emerge to the surface - before going under again.

His friends told police that they watched him disappear under the water and then emerge to the surface - before going under again. Photo: 7 News

It's believed he was part of a group of foreign nationals who had been drinking at a nearby hostel before they all decided to jump from the bridge.

"This appears to have been a drunken stunt, unfortunately," a Queensland Police spokesman said.

"They had agreed between themselves that they were going to jump off the bridge for a bit of fun and to cool down," he said.

"The 30-year-old British national - the young man in question - jumped off the bridge first.

"The other fellows said he took a running jump from three or four metres away, went under the water, he came back up again, rolled on his side and went back under the water and he hasn't been seen since."

A major land and water search is underway with water police scouring the river and police on foot searching the river banks. Photo: AAP

Officers have contacted the man's family in the UK as they continue to scour the river for him.

A major land and water search is underway with water police sweeping the river and police on foot searching the river's banks.

Morning news break - January 18