Laos: Australian Josh Richards joins search effort for missing villagers in cave in Xaisomboun province

The villagers who have been missing in a cave in Laos for more than a week have slim chances of survival.

Cave diving expert Arnold Dix told Sunrise he believed the odds were about 10 per cent.

“This is the dice stacked against everybody here,” he said.

The group of seven became trapped inside the cave in Xaisomboun province after entering on May 19, when flash flooding triggered by heavy rain cut off the exit, according to Lao and Thai rescue teams involved in the operation.

Five have been found while searches continue for the remaining two.

Mr Dix’s comments come after experienced Australian diver Josh Richards travelled to Laos on Thursday night.

The Adelaide man will join the mission to rescue the five trapped men and continue the search for two others who remain missing.

“Being included in this is really about having a strong connection with Mikko Paasi, the lead cave rescuer who’s out in Laos right now, and being kind of a small, wiggly guy who squeezes into small spaces,” Mr Richards told 7NEWS.

Mr Richards has spoken with those on the ground and said the trapped villagers are “very tired, very hungry, but generally in good spirits”.

“Obviously they would like to get out of where they are at the moment,” he said.

“That’s gonna take some time to organise, but they’re generally in good spirits.

“The other two that remain missing, it’s very unclear where they might be.

“Some hopes are fading on that front, unfortunately, but very, very grateful that we’ve managed to find five so far.”

Mr Richards said the rescue mission will be “tricky”, given the narrow tunnels they will have to squeeze through, the potential of flooding and a lack of visibility he compared to “diving in coffee”.

He added that he was feeling “scared”.

“So this mine cave is quite unstable. It’s predominantly clay, which means the roof is not properly supported. It is partially flooded,” Mr Richards said.

“The Laos authorities are currently trying to pump as much water out as they possibly can to try and reduce the risk but at this stage it sounds like there’s still a significant sump of water that we’ll need to try and get people out through in order to get them out of the cave.”

The tunnel runs about 350m long and close to 30m of it is currently under water.

Mr Richards said he likely got the call up because of his short-stature and said others contacted were predominately from south-east Asia.

Many parallels have been drawn between the current rescue mission and the 2018 rescue of a junior football team and their coach who became trapped in a cave in Thailand after heavy rain caused flooding.

“Tham Luang in Thailand was a predominantly limestone and sandstone cave, so reasonably well supported,” Mr Richards said.

“However, this is mud,” he said of the Laos cave.

He said this cave was “significantly smaller” than the one in Thailand, both in length and size.

Five of the seven villagers were located alive deep inside the cave system on Wednesday, local time, prompting emotional scenes.

“I’m still shaking. Our team made it happen,” Bounkham Luanglath from the Lao organisation Rescue Volunteer for People said in a voice message after the discovery.

The cave sits in the mountainous Longcheng district of Xaisomboun province, roughly 120 kilometres north of Vientiane, where steep terrain, heavy rain and dangerous conditions have complicated rescue efforts.

Social media footage posted by rescuers shows the difficult approach to the cave, involving a four-kilometre trek through rugged terrain before reaching a narrow, rocky entrance barely wide enough for one person to pass at a time.

Authorities have not confirmed why the villagers entered the cave. However, it has been said locals were known to visit the area in search of gold despite repeated warnings about the dangers of entering during unstable conditions.