MELBOURNE (AFP) - Australian police were questioning a man on Tuesday (Nov 23) over the disappearance of two campers who vanished from their burnt-out campsite in a rugged alpine region 20 months ago.

The 55-year-old man was arrested on Monday afternoon, police said, as part of investigations into the disappearance of Mr Russell Hill and Ms Carol Clay, both aged in their 70s.

The pair were last heard from in March last year, when Mr Hill made a radio call to friends from Wonnangatta Valley, part of a national park in the southern state of Victoria.

Other hikers discovered their empty campsite, with the charred remains of a tent and fire-damaged car, the following day.

Five people - including Ms Clay and Mr Hill - have been reported missing in the area since 2011, according to The Age newspaper.

Following the disappearance, police combed through bushland for clues, and the family of the missing pair last month issued emotional pleas for information.

"We can't grieve for someone if you don't know if they're really missing or dead," Mr Hill's daughter, Debbie, said in video released by police.

"It's just left a really big hole, a deep hole."