The August 17 bombing killed 20 people, the majority ethnic Chinese tourists, raising the possibility of a link to militants or supporters of the Uighurs, an ethnic group who say they face heavy persecution in China.
Read: What's in a name? Thais avoid linking Uighurs to Bangkok blast
A month earlier Thailand had forcibly deported more than 100 Uighur refugees to China, sparking international condemnation as well as violent protests in Turkey, where nationalist hardliners see the minority as part of a global Turkic-speaking family.
Police however blame a gang of people smugglers for the attack, motivated by revenge for a crackdown on their lucrative trade through Thailand, a motive which has been widely dismissed by security experts.
Read: Thai police seek 'Uighur' man over Bangkok bomb
"The cause was the human trafficking networks -- networks transferring Uighurs from one country to another. Thai authorities destroyed or obstructed their human trafficking businesses," Somyot Poompanmoung told reporters on Tuesday, explaining the apparent motive for the attack.
It was the first time Thai police have formally referenced the Uighurs in relation to the case, after issuing a retraction of a mention of the group over the weekend.
Analysts say Thailand is keen to avoid naming Uighurs for economic and diplomatic reasons.
Chinese visitors are a lynchpin of the tourist industry, and Beijing remains one of the increasingly isolated Thai junta's few international allies.
But arrest warrants, passports and travel itineraries of the main suspects all point towards the involvement of militants from the ethnic group or their supporters.
Nearly a month on, Thailand has two foreigners in custody and a dozen arrest warrants issued.
One of the two suspects in custody, Yusufu Mieraili, was arrested with a Chinese passport that gave a Xinjiang birthplace.
Almost all the other identified suspects have Turkish sounding names or links.
Mostly Muslim Uighurs have long accused Beijing of religious and cultural repression in China's far western Xinjiang region, with hundreds of refugees believed to have fled in recent years, often heading to Turkey via Southeast Asia.
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