With more rainfall expected, Thai rescuer Kengkad Bongkawong said Thursday that teams were racing to remove water from the cave.

‘If we are able to pump out a lot of water tonight, we will begin the extraction tonight,’ he wrote on social media.

‘But if it is deemed too risky after an assessment, we will reconsider.’

Even getting to the site will be a challenge, Paasi said: ‘The environment is extremely remote and hostile that starts with [a] 4km jungle track to the site.

‘When inside the mine you have to navigate hundreds of metres of constant restrictions, flood waters, collapse hazards and high risk of contaminated air quality.’

So far, rescuers have cut an access road, installed air flow and water pumps and even a WiFi connection to the first chamber of the cave complex.

Foreign rescuers – including two divers involved in the dramatic 2018 retrieval of a youth football team from a flooded cave in Thailand – joined Laotian volunteers this week after local groups requested specialist personnel and equipment to aid efforts.

Kengkad said a Malaysian cave diver was one of the latest foreigners to join the rescue operation.

Additional divers from Japan, France, Indonesia and Thailand were expected to arrive on Friday ‘to prevent emergencies, including the risk from additional rainwater expected to flow in tomorrow’.

The cave system, located in a remote mountainous area, extends deep underground, with multiple levels and tight tunnels.