"We plan to bring out four boys and (the) coach," rescue chief Narongsak Osottanakorn said, adding "a doctor, and three (Thai Navy) SEALS" who have stayed with the group since they were found more than a week ago will also leave the cave today.

Officials said on Tuesday that the first eight boys rescued from a Thai cave are in good mental and physical health and are asking for chocolate, although two were on antibiotics after being tested for pneumonia.

"Everyone is in a good mental state," Jesada Chokedamrongsuk, permanent secretary of the public health ministry, told reporters at Chiang Rai hospital.

"None of the eight boys has a fever today," he added in the clearest update yet on the condition of the boys rescued from Tham Luang cave.

The boys, aged 12-16, were the first to be extracted on Sunday and Monday, while the final four and their coach spent a 17th night inside.

Experts had warned of possible long-lasting damage from the ordeal, either through psychological trauma or infections caught in the cave.

Jesada said the group had been given x-rays and blood tests, adding that two presented suspected symptoms of pneumonia but were given antibiotics and were "in a normal state".

He said the group can eat, move about, and talk.

"They (all the boys) will have to stay in the hospital for one week to wait for their results and to see if anything changes," he said.

Thongchai Lertwilairattanapong, Inspector General of the Public Health Ministry, said the first four boys taken out on Sunday were eating normal and plain food.

"They're asking for chocolate. We can see that everything is okay as they're eating well," he said.

The boys remain in quarantine but some of their parents have been able to see their children through the glass.

Thailand has been riveted by the dramatic rescue mission to save the "Wild Boars" team after they first got trapped in Tham Luang more than two weeks ago by rising floodwaters.

Rescuers are racing to extract the rest of the squad and their coach as heavy rains pick back up in the northern province, threatening to complicate the last phase of the mission by reflooding the cave.

eNCA/AFP