Foreign divers, soldiers join rescue at Tham Luang cave

US military personnel arrive at Tham Luang cave in Mae Sai district, Chiang Rai, on Thursday to assist in the rescue operation for the missing children's football team and their coach. (AFP photo)

CHIANG RAI: A team of US military personnel and British divers joined rescue efforts at the flooded cave where 12 children and their football coach have been trapped for five days as heavy overnight rains hampered the search.

Flood waters seeped into a second chamber of Tham Luang cave in Mae Sai district in Chiang Rai forcing some of the rescue divers to turn back, according to officials.

The children, aged between 11 and 16, went into the cave on Saturday and were trapped when heavy rains flooded the main entrance.

Around 1,000 navy "seals" divers, police, soldiers, border guards and officials have been mobilised for the around-the-clock rescue in a mountainous area near the Lao and Myanmar borders.

A team of American military personnel from the US Pacific Command, including pararescue and survival specialists, arrived at the site overnight to help rescue operations, according to an embassy spokeswoman.

"Operators are trained in personnel recovery tactics and techniques and procedures," Jillian Bonnardeaux told AFP.

"Essentially what they're looking at is assessing with the Thai authorities the potential courses of action and complementing the efforts underway," she added.

Three British expert cave divers arrived at the scene late Wednesday and entered the cave in full kit before emerging about an hour later.

"We've got a job to do," diver John Volanthen said as he went into the tunnel, declining to speak further.

Sniffer dogs

Exhausted relatives have been camped out near the main cave entrance for days desperately awaiting news about the missing team and their 25-year-old coach.

"I'm sad. I want (my son) to be safe, we've heard nothing from officials yet," Mr Thinnakorn, the father of a 12-year-old in the cave, told AFP.

Heavy rains overnight caused water levels to rise even as several high-pressure water pumps were installed inside the cave to drain the caverns.

The flooding kept rescuers out of the tunnels as heavy rains fell overnight.

"The divers are now ready to go in as soon as the water drops to a suitable level," Thai NavySEAL said on their Facebook page on Thursday.

Border guards with police dogs scoured the site for new openings into the cave, which is several kilometres long.

Families brought clothing belonging to the kids to help the sniffer dogs find the team.

Search teams found three new entry holes this week, but only one of the chimneys was accessible.

Tham Luang cave is a popular draw for local visitors during the dry season, though a sign at the entrance warns tourists not to enter during the wet season from July to November.

Official said the football team and their coach Ekkapol Janthawong have been in the cave many times before and know the site well.

Photos on Ekkapol's Facebook page showed him with some young footballers in the cave in 2016.

The complex cave is infamous for being a tough site for skilled divers because of its complicated network of tunnels and pools.