A young platypus has been euthanased after it was discovered bound up in hairbands in a river in Victoria's Alpine Shire.

Key points: The platypus had three bands around its neck and front leg

The platypus had three bands around its neck and front leg It's believed the juvenile got tangled in the bands while hunting for food near the river bank

It's believed the juvenile got tangled in the bands while hunting for food near the river bank Litter poses a serious threat to platypuses living in waterways, experts say

The platypus, a young female, had been entangled in three elastic bands which severely restricted its movements.

It was discovered by walkers in Bright and was in visible distress, Jo Mitlehner wrote in a post on the Staghorn Wildlife Shelter Facebook page.

"She had discarded hairbands constricting her neck and front leg," she said.

"The wounds were down to the bone and recovery from them impossible."

Ms Mitlehner said the platypus probably got stuck in the bands while searching for food. ( Facebook: Staghorn Wildlife Shelter )

Ms Mitlehner said nothing could be done to save the platypus, which was put down by a nearby vet on Saturday.

On the scene was Australian Platypus Conservancy biologist Geoff Williams, who happened to be in the area running information sessions on the threats facing platypus populations.

He told the Canberra Times the platypus probably only left its nest about two months ago and was living in "agony" since being caught in the bands.

Mr Williams said litter was becoming a serious threat for platypus populations.

"Studies in Melbourne have shown one in ten platypuses have something caught around them and in some waterways it's as high as one in three," he said.

The bands were caught around its neck and leg. ( Facebook: Staghorn Wildlife Shelter )

Ms Mitlehner said it appeared the platypus became entangled in the hairbands while looking for food near the banks of the river.

"Platypus can thrive in waterways close to humans so it is essential we learn to stop littering our waterways," she said on Facebook.

"This is the third platypus retrieved from the Ovens River in Bright with life threatening injuries from litter/hair bands.

"Maybe signage outlining this issue would be appropriate in places … particularly where tourists congregate?"

Last year, experts raised concerns the platypus was vulnerable to extinction, with conservation efforts hampered by a lack of knowledge about the wild population.

"There is no reliable way of estimating platypus numbers, even at a local scale," Centre for Environmental Stress and Adaptation Research senior ecologist Josh Griffiths said.

"There's a number of areas where they're extremely vulnerable."

Ms Mitlehner reminded people to report any sightings of platypuses to the Australian Platypus Conservancy, which can be accessed by Facebook.