A large-scale search effort is under way for a man who was swept away by a Canterbury river while out hiking.

Detective Cam Ellis from Christchurch Search and Rescue said police received a report the man was “swept downstream” just after noon on Thursday.

The man and his friend were hiking on the Cass-Lagoon Saddle track in Craigieburn Forest Park, Selwyn.

“While attempting a river crossing the man has fallen and been swept downstream,” said Ellis.

The man’s friend was able to make it back to State Highway 73 / West Coast Rd, where a concerned passerby stopped to help and contacted police.

Ellis said the missing man’s friend received minor injuries and was transported to Christchurch Hospital.

A search of the river and the surrounding area for the man was unsuccessful on Thursday and the teams continued into the night.

Another search started on Friday morning, but Ellis said the conditions were hazardous.

“Police, along with dog units, Land Search and Rescue teams, rescue helicopters from Garden City Helicopters and Main Divide Helicopters, and North Canterbury Coastguard, conducted searches of the river and surrounding areas; however, no one was located.

“I want to commend the hard work of all those involved in the search.

"Conditions are hazardous, and Land Search and Rescue volunteers along with Police search teams are currently working through snow, flooded rivers, and an alpine environment to search for the missing man,” Ellis said.

-Allied Media