Two more were still inside the cave but authorities were confident of getting them out by Tuesday evening through a claustrophobic network of tunnels that in some places were completely filled with water.

"(They) will be extracted today," rescue chief Narongsak Osottanakorn told reporters on Tuesday morning.

The hoped-for final chapter in an ordeal that has gripped the world came after elite foreign divers and Thai Navy SEALs escorted eight members of the "Wild Boars" football team out of the Tham Luang cave in northern Thailand on Sunday and Monday.

Then on Tuesday afternoon multiple sources involved in the operation said three more had been escorted out. However it was not clear if the 25-year-old coach was among them or if he remained inside.

The 12 boys, aged from 11 to 16, and their coach, ventured into the cave on June 23 after football practice and got caught deep inside when heavy rains caused flooding that trapped them on a muddy ledge.

They spent nine harrowing days trapped in darkness until two British divers found them.

Authorities then struggled to devise a safe plan to get them out, mulling ideas such as drilling holes into the mountain or waiting months until monsoon rains ended and they could walk out.

With oxygen levels in their chamber falling to dangerous levels and complete flooding of the cave system possible, rescuers pushed ahead with the least-worst option of having divers escort them out through the extremely narrow and water-filled tunnels.

The ups and downs of the rescue bid has entranced Thailand and also fixated a global audience, drawing support from celebrities as varied as US President Donald Trump, football star Lionel Messi and tech guru Elon Musk.

The emergence of the second batch of four boys on Monday evening was greeted with a simple "Hooyah" by the SEAL team on their Facebook page, an exclamation that lit up Thai social media.

Positive medical reports on the rescued group further fuelled the sense of joy and optimism.

"All eight are in good health, no fever... everyone is in a good mental state," Jedsada Chokdamrongsuk, permanent secretary of the public health ministry, said at Chiang Rai hospital where the boys were recuperating on Tuesday morning.

However the boys will remain in quarantine until doctors were sure they had not contracted any infections from inside the cave.

Experts warned that drinking contaminated water or otherwise being exposed to bird or bat droppings in the cave could lead to dangerous infections.

But the early signs on the initial eight were promising, with X-rays and blood tests showing just two had signs of pneumonia and that they were in a "normal state" after taking antibiotics, Jedsada said.

Some had even asked for "bread and chocolate spread", he added.

Following a similar pattern as the previous two days, the divers ventured back into the cave at 10:00am (0700 GMT) on Tuesday, Narongsak told reporters.

However, unlike Sunday and Monday when only four were brought out each day due to logistical constraints, rescuers would try to extract all of the remaining five in one operation, Narongsak said.

A doctor and three SEALS who had stayed with the footballers would also come out on Tuesday, he added.

The escape route was a challenge for even experienced divers. The boys had no previous diving experience so the rescuers trained them how to use a mask and breathe underwater via an oxygen tank.

One fear had been that they would panic while trying to swim underwater, even with a diver escorting them.

Although there have been no major reported complications during the initial rescues, the death of a former Thai Navy SEAL diver who ran out of oxygen in a flooded area of the cave on Friday underscored the dangers of the journey.

"I cannot understand how cool these small kids are, you know? Thinking about how they've been kept in a small cave for two weeks, they haven't seen their mums," Ivan Karadzic, who runs a diving business in Thailand and has been involved in the rescue mission, told the BBC.

"Incredibly strong kids. Unbelievable almost." (AFP)