A fake passport racket uncovered in a raid by police, who also found a dismembered body in a freezer in a Bangkok house, has drawn the interest of the United States' Federal Bureau of Investigation (FBI), sources say.
Three men arrested in the house on Sept 23 had several fake passports, which were provided by a Pakistani national now jailed in Thailand, according to sources familiar with the investigation.
The sources, who spoke on condition of anonymity, said 61-year-old Babu Rafiq, arrested in Bangkok in April last year, had been told to provide the fake passports by someone in Pakistan whom security agencies believe may be the racket's kingpin.
The fake passport industry that Bangkok has long been known for has global tentacles. US and European passports are in particularly high demand as they commonly enable visa-on-arrival entry.
The trio arrested in the Bangkok raid had fake US and British passports, prompting the FBI to send investigators to Bangkok last week.
They have been identified as Aaron Thomas Gabel, 33, and James Douglas Eger, 66, both American, and Peter Andrew Colter, 56, a Briton. One of them is said to go by several names. Police have yet to determine the identity of the dead man or when and how he was killed.
They also found three handguns, passport-printing equipment, and chemicals, including pharmaceutical ingredients and sulphuric acid. At least one of the dozen-odd passports found had travel stamps for Malaysia and Singapore.
The Pakistanis involved in the fake passport ring are said to be linked to at least one individual, Atiq ur Rehman. He is suspected of having provided passports to the Al-Qaeda operatives who set off a series of coordinated bombings on commuter trains in Madrid in 2004.
Atiq, who was arrested in June this year, is now in Thai custody. France is trying to extradite him in connection with terror investigations there.
Thai investigators are "probing the angle that Babu, on instructions from someone in Pakistan, was the one who made the fakes for the foreigners" in the Bangkok house, a security source said.
"It may be premature to link this with terrorism, but it is gangs like this that supply criminal and terrorist elements not just with passports, but with fake visas too," he added.
Investigators are particularly concerned about the use of high-quality fake passports and visas by Islamic State in Iraq and Syria militants.
In an e-mail to The Straits Times, Jakarta-based security analyst Sidney Jones wrote: "There is no question that access to fake travel and identification documents facilitates terrorism, just as it facilitates human trafficking, drug trafficking and various forms of transnational crime."
She added: "The process frequently involves international syndicates, but can just as easily involve a local cell of corrupt immigration officials looking to make easy money on the side."
Thai security agencies have been fighting a running battle to expose fake passport rackets.
In 2010 they arrested Pakistani "Tony" Muhammad Ather Butt, whose racket spanned two continents and was linked to both Atiq and the Pakistan-based Lashkar e Taiba terror group.
In 2014, two Pakistanis and two Thai women were arrested on charges of running a fake passport ring using an Indian restaurant in Bangkok as a front.
Nabbed earlier this year was Hamid Reza Jafary, a Bangkok-based Iranian nicknamed "The Doctor" for his skills in forging passports, mostly for illegal migrants.