An Australian man has been arrested over the murder of a teenage girl whose naked body was found inside a suitcase alongside a railway line in Thailand.

The 46-year-old man, from Ballarat, Victoria, was arrested for the murder of 17-year-old Thai girl Tunchanok Donhomla as he allegedly tried to board a plane at the Suvarnabhumi International Airport in Bangkok on Friday evening, local media reports.

His arms and neck were allegedly covered in scratch marks at the time of his arrest.

According to local media, the man allegedly picked up the teenager from the Beach Road vice strip in Pattaya – a popular coastal resort city around two hours from Bangkok – in the early hours of Thursday morning before the pair traveled to the man’s hotel.

CCTV footage shared online by Thai media shows the pair holding hands while walking past a security guard and into an elevator around 3:30 a.m. on Thursday.

Police Colonel Anek Sarathongyu, Superintendent of the Pattaya City Police Station, told Viral Press, “The cameras show that nobody else entered the room. There were signs of a struggle inside.”

Hours later, the man can be seen in footage leaving the hotel with a black suitcase around 9:30 p.m., Viral Press reports.

Surveillance footage reportedly shows the man riding a motorcycle with the luggage strapped to the back.

Donhomla was reported missing by her friends at 5:00 p.m. on Friday, ViralPress reports.

Two hours later, the Australian man was arrested by police at the airport and transported back to Pattaya.

Around 11:00 p.m., officers reportedly found Donhomla’s naked body bent double in a 26-inch black suitcase alongside a railway line, around ten minutes from the hotel where the man had been staying.

Colonel Sarathongyu said, “The victim went to the hotel room with the suspect, but she was not seen leaving. Then, later, the Australian came out with a suitcase.

“The victim was found dead inside the same suitcase. She was completely naked, her face showed signs of severe assault, with swelling and bruising covering the entire face, and blood was flowing from her mouth and nose.

“The physical characteristics and tattoos on the body matched those of the girl on CCTV with the suspect.”

Footage shared online shows members of the police forensic team gathering around and examining the luggage.

Video obtained by ViralPress shows the moment a reporter at the police station asked the man why he killed the girl.

“I don’t know how, no,” he replied.

When questioned about visible scratches on his neck, he said, “I have the same on the other side, I think it’s a spider, they always get in here.”

Colonel Sarathongyu said the “suspect has initially been charged with taking a minor for the purpose of committing an indecent act.”

“We believe he killed her, and he is being questioned on suspicion of murder.

“He has fingernail scratches across his body that are consistent with a struggle, but he denies killing her. He said that she disappeared from the room while I was asleep and unaware of anything.”

The man claims to be innocent, local media reports. He has not been charged with murder.

In Thailand, murder can carry the death penalty or life in prison.

News.com.au has contacted the Department of Foreign Affairs & Trade for comment.