An 18-year-old’s Kiwi’s first overseas trip has ended with him detained in a Thai jail after a watch incident at airport security.

Loukas Rainger is in prison at Thailand’s Surat Thani after allegedly taking a watch that was left in a tray during a security bag check in the city’s airport, Stuff reported.

The Tauranga teenager was due to return home through Suvarnabhumi Airport in Bangkok after travelling for a month with his friend when he was stopped by immigration on Thursday, his mother Natasha Rainger told Stuff.

Natasha, who is also in Bangkok having undergone surgery, said her son told her he had picked up the watch two weeks earlier at an airport in Surat Thani.

“He was told by immigration that there was a warrant out for his arrest.”

Stuff reported that Loukas told his mother he has been left “completely confused” by the turn of events.

He told his mum the watch was on the airport tray he had his bags on in security, so he “just picked it up too”.

Natasha claimed police took Loukas into custody, retrieved his checked bag before it reached the plane and detained him overnight at the Bangkok police station.

He was then handcuffed to a train for several hours while he was taken back to Surat Thani and questioned by officers, where he has remained since.

Bail was denied because Loukas didn’t have the right visa.

The court has demanded proof of a three-month accommodation booking in Thailand at an upcoming hearing, with Natasha’s own visa due to expire in mid-August.

“I haven’t rested or slept since this happened … I’m exhausted, I’m on auto-mode," she told Stuff.

She said her husband Mark Rainger stayed at home in Tauranga to take care of Loukas’ younger brother.

Managing partner at Phuket’s Lawyer Republic Werabhat Hemthansarp, who is representing Loukas, said the 18-year-old had been charged with “theft at an airport”.

“It is more serious than theft because it happened at an airport,” he said to Stuff.

Natasha and Mark Rainger, as well as Werabhat Hemthansarp have been approached by the Herald for comment.

Hemthansarp said he was in the process of changing Loukas’ visa to allow him to apply for bail, as well as arranging a $1000 compensation payment for the owner of the watch.

Bail was expected to be approved in the next 24 hours.

According to Natasha, Loukas apologised to the owner from prison and was told “she accepted the apology and will accept the $1000″.

She claimed he didn’t act maliciously.

“He didn’t think, he’s inexperienced, young. He’d been on a long boat trip just right before and had been really sick. He should have left it or handed it in ...” she told Stuff.

The situation had left the family “completely overwhelmed and in disbelief”.

“I’m honestly [at the point where I] would give my life to get him out of there,” she said.

Her son, who was fresh out of school, was on his OE before taking up an electrical apprenticeship, she said.