One of the two men arrested over last month's deadly Bangkok bombing has admitted to a charge of possessing explosives, police said on Monday, in the first confession over the unprecedented attack on Thailand.
Police say the suspect, Yusufu Mieraili, was arrested last week near the border with Cambodia.
"We have informed him of the charge. He acknowledged and confessed to the charge," national police spokesperson Prawut Thavornsiri told reporters.
Police have not revealed his nationality, although he was caught in possession of a Chinese passport with a birthplace listed as Xinjiang -- home to the country's oppressed Uighur Muslim minority.
Mystery surrounds the alleged bombers' motive but speculation has hardened on links to China's Turkic-speaking Uighur minority.Thailand deported scores of Uighur refugees to China early in the summer, prompting protests in Turkey where some nationalists hold a deep affinity with the minority group.
A second man identified as Adem Karadag has already been charged over the crime after he was caught in a flat in a Bangkok suburb with bomb-making paraphernalia and dozens of fake Turkish passports.
Police have said neither man is thought to have physically planted the bomb on August 17 at a religious shrine in downtown Bangkok that killed 20 people.
But they are confident the pair are involved in the network blamed for the attack, which rocked the capital and dented faith in Thailand's key tourist sector.
After nearly two weeks without progress on the bombing, police made what they said was a breakthrough following a raid on the flat in Bangkok's eastern suburbs.
There they found Karadag. That arrest led to Mieraili who was picked up three days later on the Cambodian border.
The alleged confession of one of the gang's key members came as police said they had also issued two new arrest warrants.
The total number of people wanted for suspected involvement in the deadly attack stands at eleven -- on top of the two arrested foreigners.
They include a Thai Muslim woman and her Turkish husband, both of whom are believed to be in Turkey.
Prawut told reporters one of the new warrants is for a foreign man of unknown nationality called Abdullah Abdullahman.
The second is for an unnamed foreigner seen on CCTV buying items from a department store close to where the two arrested suspects allegedly stayed.
Prawut did not detail what items the man had bought but said the new warrants were based on witness testimony and the interrogation of the two arrested men.
Both men are wanted on a charge of illegal possession of explosives, he added.
The shrine that was hit by the blast is known for its popularity among Chinese worshippers.
The majority of those killed in Thailand's worst single mass casualty attack were ethnic Chinese visitors from across Asia.
But Thailand's police and junta have been at pains to rule out the idea that the Chinese were deliberately targeted.
Instead Thai police say the bombing was carried out by a criminal network motivated by revenge after a people-smuggling trade was disrupted.
Analysts have voiced scepticism over that motive, saying Bangkok criminals have never carried out such extreme violence.
The Chinese visit Thailand in far greater numbers than any other nationality. Tourism accounts for at least 10 percent of GDP and remains one of the few economic bright spots in the junta-run kingdom.
While Uighur militants have carried out a series of increasingly bold attacks inside China, usually using rudimentary weapons such as knives, they are not known to have ever attacked people overseas.