The Tasmanian father and brother of a Australian man missing in a remote Malaysian jungle have travelled to the region to join the search for the 25-year-old backpacker.
Andrew Gaskell went hiking in the remote Mulu National Park in the Sarawak region on October 18 and hasn't been in touch with family or friends since.
He indicated at the time he'd be walking in the area - which has poor mobile phone coverage and is known for its caves and vast formations - for about a week.
Acting Inspector Darren Latham on Monday said Tasmania Police was liaising with Malaysian police as they tried to establish Mr Gaskell's whereabouts.
Search efforts in the national park are continuing with Malaysian police running the investigation.
Police were alerted to Mr Gaskell's disappearance by family members living in Tasmania who had been in constant contact with the solo traveller during his overseas trip, Act Insp Latham told reporters.
The 25-year-old grew up in Hobart but has lived in Cairns for the past three years.
"As the days have gone on it is certainly concerning - we obviously hope that Andrew is well and can make his way out of the jungle," Act Insp Latham said.
Tasmania Police also called on anyone who had friends backpacking in Malaysia to share Facebook posts about the missing man in case they've seen him in recent days.
Volunteers from a rural village that had contact with Mr Gaskell before he disappeared joined the search in the national park over the weekend.
Mr Gaskell's family on Sunday said they were "overwhelmed" by the Malay people's kindness and generosity of spirit.
Tasmanian Police are also working with the Department of Foreign Affairs and Trade.