Born in Myanmar, raised by Christian teachers in Thailand, and now trapped in a flooded cave for 13 days, Adul Sam-on's unflinching politeness and startling ability to speak English is capturing hearts.

Images of the wide-eyed teen were beamed around the world when he was discovered alive with the rest of his young football team deep inside the Tham Luang cave.

He remains stuck in the bowels of the mountain as rescuers work out how to get the 12 boys and their coach out safely, a race against time with heavy rains expected to return soon.

"I'm Adul, I'm in good health," the rake-thin 14-year-old said in Thai in a video that emerged hours after the group was discovered, offering a traditional Thai "wai" greeting — trademark politeness, his teachers say.

"The first thing that comes to mind when I talk about him is his nice manner. He gives a 'wai' gesture to every teacher he walks past, every time," his instructor Phannee Tiyaprom at Ban Pa Moead School told AFP.

Adul is also being praised for his English skills in a country where less than a third of the population speaks the language.

He was the only one able to communicate with the British divers that discovered the boys on Monday night.

"What day is it?" he shouted, telling the divers they were hungry, in footage broadcast around the world after the agonising search for the boys.

Born in Myanmar's self-governing Wa State, young Adul — who also speaks Thai, Burmese, and Chinese — has been at the school since he was seven years old.

He left his family behind to get a better education in northern Thailand, but his parents still visit him at the Christian Church where he's been taken in.

Wa State, a self-ruled region not recognised internationally — nor by Myanmar — is not allowed to legally issue passports.

Fighting between ethnic rebels from United Wa State Army and Myanmar troops has historically driven thousands from the state seeking safety and greener pastures, including to nearby Thailand.

Adul is among more than 400,000 people who are registered as stateless in Thailand, according to the UN Refugee Agency (UNHCR) — though some estimates put their numbers at 3.5 million.

"Whilst some progress has been made, stateless people in Thailand continue to face challenges accessing their basic rights," UNHCR spokeswoman Hannah Macdonald told AFP.

With no birth certificate, no ID card and no passport, Adul cannot legally marry, get a job or bank account, travel, own property or vote.

Thailand has vowed to register all stateless people by 2024, but until then people like him remain stuck in legal limbo.

But he refuses to let his status hold him back.

The passionate footballer also loves to play the piano and guitar, and is an accomplished student too.

"He's a gem," school director Phunawhit Thepsurin told AFP.

"He's good at both studying and sports… he's brought our school several medals and certificates from his achievements."

FIFA boss invites Thai cave boys to World Cup final
Moscow (AFP) July 6, 2018 –

FIFA president Gianni Infantino has invited the Thai boys' football team trapped in a cave to the World Cup final, as messages of support poured in from top players.

Infantino said he hoped the Wild Boars team, who were stranded by rising floodwaters two weeks ago, would be rescued in time to watch the final in Moscow on July 15.

"If, as we all hope, they are reunited with their families in the coming days and their health allows them to travel, FIFA would be delighted to invite them to attend the 2018 World Cup final as our guests," he wrote in a letter to the head of the Football Association of Thailand.

"I sincerely hope that they will be able to join us at the final, which will undoubtedly be a wonderful moment of communion and celebration."

The Thai footballers, aged 11-16, have been stuck in darkness deep underground after setting off to explore the cave with their 25-year-old coach after training on June 23.

The players remain trapped despite being reached this week by cave-diving rescuers, who released footage of them looking emaciated but calm, some wearing football shirts.

Their harrowing ordeal coincides with the World Cup in Russia and it has not escaped the attention of players.

"I've been speaking about it with a few of the boys," said England defender John Stones, according to British media.

"It's so sad to see where they are and we hope they get out safe and sound."

Japan's World Cup squad tweeted a video urging the team to "Hang in there!", while Brazil legend Ronaldo called their plight "terrible".

"The world of football hopes that someone can find a way to take these kids out of there," he said, according to CNN.

Liverpool manager Jurgen Klopp urged them to "stay strong and know we are with you", in a video message sent to CNN.

"We are following all the news and hoping every second that you see daylight again," Klopp said. "We are all very optimistic that it will happen, hopefully in minutes, hours or the next few days."

Meanwhile the Croatian Football Federation said it was "awed" by the team's calm under pressure.

"We are awed by the bravery and strength that these young boys and their coach have shown amidst such frightening circumstances," it said on its website.

Many fans on social media said the boys deserved the World Cup trophy for the way they have handled their ordeal.