Tasmania Police investigating attack in Trevallyn Reserve

While shaken by the incident, the woman was unharmed and was at work on Monday.

Launceston Detective Senior Sergeant John Parker said the woman had been walking near Duck Reach Power Station and turned on to Lower Snake Gully Track, which is also known as the Daffodil Walk, and to walk to The Basin in Cataract Gorge.

About halfway along the Lower Snake Gully Track, she was approached by a man who "grabbed her in a headlock and put his hand over her mouth".

"She has been able to subdue him and screamed. He has let her go and she ran off down the track," Sergeant Parker said.

The man kept walking up the track.

Another woman saw the man on the track and spoke with the woman after she was attacked.

Tasmania Police would like to speak with her as she may be able to help identify the man.

"She was wearing a t-shirt which had a brass band motif on it."

The man is aged between 25 and 30 years, with blonde, scruffy hair, slight build, about 70 kilograms, wearing a khaki long-sleeved shirt with dark pants and canvas-type shoes.

"We would like to speak to anybody who may know who that person is," Sergeant Parker said.

The person could be living close by, he said, with Tasmania Police following up reports of a person in that area who "appears to be homeless".

"It is quite possible that man has been staying in the area. He may be homeless."

Sergeant Parker said this type of incident at the gorge was "very rare".

"We've had no other reports of this type of crime, so we would suggest it's a spur-of-the-moment attack," he said.

"Walk in pairs if you can, but we shouldn't be put off by this type of incident. We should all feel pretty safe in our environment."

Anyone with information should contact Launceston CIB on 131 444 or report anonymously to Crime Stoppers on 1800 333 000 or crimestopperstas.com.au