The rescued boys have been given a clean bill of health by doctors.

They have no fever or serious ailments, said public health permanent secretary Dr Jesada Chokedamrongsuk at a press conference yesterday.

"Everyone is in a good mental state,” he told reporters in the clearest update yet on the health of the boys. The boys are alert and the group can eat, move about, and talk, he said.

Doctors are taking no chances with their physical recovery, quarantining the group, administering tetanus and rabies shots, and putting two of the team on antibiotics after they showed signs of pneumonia. They have also been given sunglasses to wear as they adjust to daylight after days trapped in the dark.

All boys, aged between 11 and 16, are being treated in an isolation ward in Chiang Rai Prachanukroh hospital. Four of them were rescued from the flooded Tham Luang cave on Sunday and four on Monday and rest of the four along with their assistant football coach yesterday.

The second group who were rescued on Monday have low body temperature and slow heartbeat. Details about the group rescued yesterday were not known.

"The first four boys' eyes are normal. For the second group (that) arrived last night, they are still wearing sunglasses. We will check later today whether their eyes have adjusted to light," said Dr Jesada.

The parents of first four boys can see them through a glass wall, but no physical contact is allowed.

When asked why the boys managed to survive so long underground before they were found by divers, Dr Jesada said: "The kids are footballers, are strong and have high immunity.”

But he said the youngsters are unlikely to be able to take up an offer to attend the World Cup final in Moscow.

Doctors said while the boys are in good shape they will go through a slow and careful recovery that will see them stay in hospital for a week.

The boys have a good appetite but are being given bland, easily digestible foods. However, doctors later relented after some of the boys asked for bread with chocolate spread.

Experts had warned of possible long-term psychological damage such PTSD from the ordeal, including the initial 10 days underground, in darkness and without contact with the outside world, reported AFP.

“It is certainly a risk and can take some time to manifest itself and make its presence known,” said Dr Andrew Watson, a specialist on rescues from mines and floods trapped. “I am not sure about children and how they will react.”