CHIANG RAI- The eight boys who were rescued from a flooded cave in northern Thailand 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 on Tuesday (July 10).

"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 eight boys, aged between 12 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 the other four on Monday.

The second group to be rescued on Monday have low body temperature and slow heartbeat.

"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.

Fifa boss Gianni Infantino had invited the 12 boys, who had football training before disappearing into Tham Luang cave on June 23, to the July 15 showpiece in a gesture of solidarity from the footballing world.

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.

"They're likely to watch it on television," said Dr Jedsada when asked about the offer to attend Sunday's match.

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.

"They're asking for chocolate. We can see that everything is okay as they're eating well," said Thongchai Lertwilairattanapong, Inspector General of the Public Health Ministry.

Doctors expect them to remain in the hospital for at least a week. They will be monitored closely to see if they pick up any infectious disease from deep within the cave.

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 Agence France-Presse.

"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."