Australian Federal Police and defence force personnel are being deployed to Thailand to assist in the search for 12 boys and their soccer coach missing in a flooded cave system for over a week.

Six AFP Specialist Response Group members who have search and rescue, and cave diving skills are on their way to Chiang Rai aboard a Royal Australian Air Force C-17 transport aircraft.

The Aussie rescuers will join the search which already has Thai navy divers, a US military team and British cave experts on board.

Australia’s foreign affairs, defence and home affairs ministers said in a joint statement late on Saturday that Australia was working closely with the Thai government and the Royal Thai Army, who are leading the search operation.

The ADF has also deployed an official to the rescue command centre in Chiang Rai as a Specialist Liaison Officer to provide operations and planning expertise.

A Department of Foreign Affairs and Trade officer is also deploying with the AFP rescue team to assist with co-ordination.

The soccer team aged between 11 and 16, along with their 25-year-old coach, entered the Tham Luang Nang Non cave in Chiang Rai on June 23 but no contact has been made with them since.

Medical teams staged drills on Saturday to prepare for their possible rescue as worries loomed over how the boys might be pulled out of the Tham Luang cave if and when they are found.

Ambulances and helicopters were on standby for the drills at the bustling rescue site in northern Chiang Rai province.

“It’s to set up a system to practice what to do until we can get them to hospital,” Chiang Rai governor Narongsak Osottanakorn said late on Friday.

As the search continues, attention has turned to their chances of survival inside a cave with little or no food and light.

The boys likely have access to freshwater - either dripping in though rocks or rushing in through the entrance - but experts warned that run-off water from nearby farms could carry dangerous chemicals or bacteria.

“If they drink the water in the caves and it makes them sick it could hasten the problem that they’re in, but if they don’t drink it then they’re also in trouble,” Anmar Mirza, co-ordinator of the US National Cave Rescue Commission said.

But even without food he said young, athletic boys could “easily live for a month or a month and a half” but the main challenge now would be mental resolve.

“The biggest issue that they’re facing right now if they’re alive is psychological because they don’t know at what point they might get rescued,” Mr Mirza said.

Officials said the boys know the site well and have visited many times before, buoying hopes that they might have trekked to a large airy chamber in the centre called Pattaya beach.