Police believe a body found in a river in Western Australia is that of a former Bay of Plenty man.

The body was located by a member of the public near Chidley Point Reserve but formal identification is yet to be completed.

Former Rotorua man Sean Mitchell went missing 10 days ago.

Sean Mitchell's family have been notified and police say there are no suspicious circumstances surrounding the man's death.

A land, air and water search for Sean, a 37-year-old mine worker, had been called off on Monday.

Police say he disappeared 10 days ago after boarding his friend's yacht alone in rough sea conditions.

Sean went missing after having drinks with friends at the Belgian Beer Cafe in Perth on Friday night, May 20.

Police say he boarded a train using his Smartrider card around 9pm, but never tagged off.

A massive search was launched on Wednesday after a passer-by found his backpack in the Swan River near Blackwall Reach on Sunday, about 2km from where he boarded his friend's yacht in Mosman Park - and reported it to police on Tuesday.

Sean had told friends he intended to sleep aboard the yacht the night he disappeared.

On Friday, police examined a dinghy they suspected Sean had boarded to row to shore on either Friday night or early Saturday but found no further clues.

During the search, vehicle and foot patrols were conducted along the shore of the river through the suburbs of Mosman Park, East Fremantle, Bicton and Attadale.

Water Police conducted boat patrols in the same areas.

Sean's body was found around 1.5km south of where he boarded his friend's yacht.

- Stuff.co.nz