Family members, monks and friends watched from a boat as the ashes of one of the 12 boys rescued from a flooded cave in northern Thailand in 2018 were released into the Mekong River.

Duangphet Phromthep, 17, died last month while attending a football academy in England.

Duangphet’s ashes floated away in a makeshift vessel, along with footballs and some of his prized possessions, in an area of the river in Chiang Rai, the country’s northernmost province, at the Golden Triangle – where the borders of Laos, Myanmar and Thailand meet – on Monday.

His body was cremated in a Buddhist ceremony in England in accordance with his family’s wishes.

Phra Khru Prayut Chetiyanukarn, abbot of the province’s Wat Phra That Doi Wao temple who led the Buddhist funeral procession, said the location is where people often scatter the ashes of their family members.

He said the Golden Triangle “is believed to contain a Naga that helps protect and takes care (of the dead) for us”.

Nagas are serpent-like mystical creatures revered according to Thai Buddhist beliefs. The Mekong River is one of Asia’s longest, spanning almost 3,100 miles, and runs through several countries including China, Vietnam, Myanmar, Cambodia, Thailand and Laos.

Duangphet, known as Dom, was found unconscious in his room on February 12 at the Brooke House College Football Academy in Leicestershire.

He died in hospital two days later.

The cause of death has not been released to the public by coroners, but police said it was not believed to be suspicious.

Buddhist prayer sessions for Duangphet took place over the weekend at Wat Phra That Doi Wao in his hometown of Chiang Rai after his ashes arrived from Britain on Sunday.

The temple is less than six miles from Tham Luang cave, where Duangphet and 11 of his Wild Boar football teammates and their coach were trapped for more than two weeks before being safely guided out by expert cave divers in a miraculous effort which captured global interest.

Adul Sam-on, a former teammate who was trapped with him in 2018, arrived in Chiang Rai on Monday from New York, where he is studying, to say his final goodbyes to Duangphet, one of his closest friends.

“Even though today was the last day of the ceremony, I’m happy I made it,” Adul said. “We were so close. We were just like brothers.”

Duangphet was described by his friends and coaches as a talented and determined player.

“He was so good at football both technically and mentally,” said Anucha Ratchacote, 17, a former teammate of Duangphet at Vachiralai Bee School in Chiang Mai.

“He wanted to play for the national team and I think he was good enough.”