"The collapse risks are high because you're constantly touching the roof, and it's hand-dug. There's no support anywhere," said Mikko Paasi, a diver who helped rescue a youth soccer team from a cave in Thailand.

Thai teams have joined the mission, as rescuers share photos of the treacherous conditions in the cave tunnel.

Seven Laotian villagers entered a cave five days ago searching for gold and were trapped inside after heavy rain triggered flash flooding.