MONTREAL (AFP) - A man who was swept over the largest of the Niagara Falls has been recovered alive, found sitting on a rock in the river below with non-life threatening injuries, Canadian police said on Wednesday (July 10).

Niagara Park police responded to a call at 4am on Tuesday about a "man in crisis" on the brink of Horseshoe Falls, a 57m-high drop.

When they arrived, the man climbed over a retaining wall into the river and was swept over the waterfall's edge, the police said.

"Male was found sitting on rocks after search of lower river w/non life threatening injuries," the police report said.

The man, who was not identified, ended up on the Canadian side of the falls, which straddle the US-Canadian border.

The incident marks the fourth time an adult is known to have survived going over without protection, according to local news accounts.

In addition, in 1960, a seven-year-old boy went over Horseshoe Falls in only a life jacket after a boating accident, and was rescued from the roiling waters below by a life ring thrown from a tour boat.

Some have also survived after going over the falls in barrels or with flotation devices, while others have died in the attempt.