Thai police are hunting for further suspects linked to Bangkok’s worst-ever bomb attack after the arrest of a foreigner allegedly involved in the plot spawned more questions than answers.

Authorities said they were tracking hundreds of phone numbers and passports after detaining the suspect in a raid in Bangkok on Saturday, but they have yet to reveal his name, nationality or any information on motive or possible accomplices. A raid on Sunday on a second address yielded no evidence, police said. 

The mystery has been intensified by officials’ continued insistence that the August 17 murder of 14 foreigners and six Thais at the Erawan shrine in the capital’s heart was no international conspiracy. Thai media reports have linked the detained man to a Turkish passport whose identity page was widely broadcast after the arrest, but the document is suspected to be a fake.

Authorities in Ankara have asked the Thai authorities for the suspect’s fingerprints and other details but have yet to hear back, a Turkish security official said. The official said that a Turkish identity card found separately during the investigation was a genuine document previously reported missing by a Turkish national.

Officials from Thailand’s police and ruling military junta did not respond to a request to comment on the alleged contact from Turkey. Bangkok has previously rejected offers of assistance on the investigation from other countries, including the US.

Gen Prawuth Thavornsiri, a police spokesman, told Thai television that authorities were investigating 1,000 numbers possibly linked to the group to which the 28 year-old detainee belonged, although he declined to identify the organisation. He said police still believe the suspect could be the man in a yellow T-shirt whom security cameras revealed dumping his rucksack at the packed shrine shortly before the blast.

The man, who police say has been in Thailand for more than 18 months, has been charged with possessing illegal explosives. Police say they found bomb-making equipment, including detonators and a metal pipe with lids, at a raid on the north Bangkok apartment where they made the arrest. Authorities say the device that ripped through the shrine was a pipe filled with explosive and ballbearings.

Gen Prawuth also said police were examining 200 passports potentially linked to the suspect’s network. Investigators say they found multiple passports during the raid, with some reports suggesting there were scores of fake documents.

Questions looming over the raid include why a foreigner involved in the bombing would remain in Thailand surrounded by incriminating material for almost two weeks after the blast.

The arrest came after almost a fortnight, during which theories about the bombing have swirled amid conflicting official information and the absence of publicised leads, save for the footage of the prime suspect arriving and leaving the shrine.

There is speculation that the bombing may be linked to the country’s long-running domestic political conflicts, or to last month’s deportation of more than 100 members of the Uighur ethnic minority group from Thailand to China.

Turkish nationalist groups have taken up the cause of the Turkic-speaking Uighurs. A mob ransacked the Thai consulate in Istanbul after the latest deportation.

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