The suspect was detained by police at Suvarnabhumi Airport after the body of the Thai teenager was found in a black suitcase next to a railway in Pattaya, according to local media reports.
The Pattaya News and other Thai and Australian outlets have identified the suspect as a 46-year-old from Ballarat.
A Department of Foreign Affairs and Trade spokesperson has confirmed it is providing consular assistance to an Australian detained in Thailand but was unable to comment further due to privacy obligations.
CCTV footage obtained by Pattaya News 24 shows the victim entering an apartment complex in the resort town with the suspect on June 25 in the early hours of the morning.
A separate camera appears to capture the suspect leaving the residential building alone later that evening, and wheeling a large black suitcase.
Local reports allege the suitcase was loaded onto a motorcycle and later found by police near a railway roughly four kilometres away.
The suspect, who was detained by immigration officials at Suvarnabhumi Airport on Friday before he was scheduled to leave on a flight to Perth, is reportedly denying any involvement in the teenage girl's disappearance.
DFAT consular staff cannot provide legal advice or intervene in legal cases in foreign countries.
Their assistance is limited to monitoring welfare in prison, accessing local legal representation and aiding communications with family.Â
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