An Australian man has been arrested in Thailand after the body of a 17-year-old Thai girl was discovered stuffed inside a suitcase and dumped near a railway line in Pattaya, in a case that has shocked both countries.

A man from Ballarat is in custody after the body of a teenage girl was found in a suitcase in Thailand.

The 46-year-old was stopped at about 9.30pm on Friday while preparing to board a Jetstar flight to Perth, according to the Nation Thailand