The 12 boys and football coach found in a partially flooded cave in northern Thailand after 10 days are mostly in stable medical condition and have received high-protein liquid food, officials said.

Video released by the Thai navy showed the boys in their football uniforms sitting on a dry area inside the cave above the water as a spotlight, apparently from a rescuer, illuminated their faces.

Chiang Rai provincial governor Narongsak Osatanakorn said the health of the boys and coach were checked using a field assessment in which red is critical condition, yellow is serious and green is stable.

“We found that most of the boys are in green condition,” he said. “Maybe some of the boys have injuries or light injuries and would be categorised as yellow condition. But no one is in red condition.”

When the group will be able to leave the cave is not known due to flooding and other factors that could make their extraction dangerous.

Experts have said it could be safer to simply supply them where they are for now. Thailand’s rainy season typically lasts through October.

Family members of the missing hugged each other and cheered as they heard they had been found.

Aisha Wiboonrungrueng, the mother of 11-year-old Chanin Wiboonrungrueng, smiled and hugged her family as news of their discovery spread. She said she would cook her son a Thai omelette, his favourite food, when he returns home.

Rescue divers had spent much of Monday making preparations for a final push to locate the lost footbal players, aged 11 to 16, and their 25-year-old coach.

Flooding trapped them after they entered the Tham Luang Nang Non cave in Chiang Rai on June 23.

Divers found the group about 300-400m past a section of the cave on higher ground that was thought to be where they might have taken shelter.

In the five-minute navy video, the boys are quiet as they sit on their haunches, legs bent in front of them. “You are very strong,” one of the rescuers says in English.

Someone asks what day it is, and the rescuer responds, “Monday. Monday. You have been here — 10 days.”

One boy, noticing the camera and hearing unfamiliar words, says in Thai, “Oh, they want to take a picture; tell him we’re hungry. I haven’t had anything to eat.”

Then the boy breaks into simple English, saying, “Eat, eat, eat,” to which another voice responds in Thai that he already told that to the rescuer.

Thailand Cave Search Thai rescue teams walk inside cave complex where 12 boys and their football coach went missing (Tham Luang Rescue Operation Center via AP)

Mr Narongsak said on Tuesday that the missing were given high-protein liquid food, painkillers and antibiotics. He said doctors had advised giving the medicine as a preventative measure.

Anmar Mirza, a leading American cave rescue expert, said many challenges remain for the rescuers. He said the primary decision is whether to try to evacuate the boys and their coach or to supply them in place.

“Supplying them on site may face challenges depending on how difficult the dives are,” Mr Mirza, coordinator of the US National Cave Rescue Commission, said in an email.

“Trying to take non-divers through a cave is one of the most dangerous situations possible, even if the dives are relatively easy. That also begets the question: If the dives are difficult then supply will be difficult, but the risk of trying to dive them out is also exponentially greater.”

Mr Narongsak said officials had met and agreed on the need to “ensure 100 per cent safety for the boys when we bring them out.”

“We worked so hard to find them and we will not lose them,” he said.

THAILAND Cave rescue A view of the boys and their coach as they are found in a cave, in Chiang Rai in Thailand (Thai Navy Seal via AP)

Prime Minister Prayuth Chan-ocha thanked the international experts and rescuers who helped locate the missing for their “tremendous efforts”.

“The Royal Thai Government and the Thai people are grateful for this support and cooperation, and we all wish the team a safe and speedy recovery,” Mr Prayuth’s office said in a statement.

The rescuers had been stymied repeatedly by rising water that forced divers to withdraw for safety reasons. When water levels fell on Sunday, the divers went forward with a more methodical approach, deploying a rope line and extra oxygen supplies along the way.

Teams have also been working to pump water out of the cave and divert groundwater, while other rescuers focused on exploring shafts above ground that might lead into the cave. Several fissures were found and teams have explored some, though none led to the missing group.

Experts in cave rescues from around the world had gathered at the site. An official Australian group has followed a US military team, British cave experts, Chinese lifesaving responders and several other volunteer groups from various countries.