Police are still unable to find 15 suspects in connection with last year’s Erawan shrine bombing that killed 20 people, an officer said on Wednesday, as two ethnic Uighur Muslims from China accused of involvement appeared at Military Court.
No group has claimed responsibility for the Aug 17 blast at the Ratchaprasong intersection tourist spot popular with visitors from China. Five of the dead were from China and two from Hong Kong. More than 120 people were wounded.
Analysts, diplomats and officials suspect the attack was linked to Uighur sympathisers angered by Thailand's deportation of more than 100 Uighurs to China the previous month.
Police ruled out "terrorism" and said the attack was retaliation for a crackdown on human smuggling.
The two suspects who were arrested -- Yusufu Mieraili and Bilal Mohammed -- are Uighur Muslims, a minority from western China who speak a Turkic language. They have denied all charges.
Police have issued arrest warrants for 15 other people, eight of whom are thought to be either Turkish or in Turkey, according to the warrants and police statements.
"We don't know where they are," deputy police spokesman Maj Gen Songpol Wattanachai told Reuters. "The perpetrators have done their utmost to escape."
Shaven-headed and barefoot, Mr Mieraili and Mr Mohammed - also known as Adem Karadag -- were led in handcuffs and leg shackles into a cramped court in Bangkok's old city.
Mr Mieraili spoke briefly to Reuters saying he expected the trial would take "a very long time". The men had marks on their foreheads which Mr Mieraili said came from coming into contact with the floor during prayer.
Three judges heard evidence laid out in 25 thick files on a table beneath them. There was no jury.
The defendants' lawyers said more than 500 witnesses could be called for the prosecution and defence, and that the high-profile trial could last a year or more.
Proceedings were laboriously translated through two interpreters from Thai to English to the Uighur language.
Police say Mr Mohammed was the man caught on CCTV footage at the shrine, sitting on bench, slipping off a bulky back-pack and walking away, just before the blast.
Most Uighurs live in China's violence-plagued Xinjiang region, where exiles and human rights groups say Uighurs chafe under government policies that restrict their culture and religion.
China denies this and blames Islamist militants for the rising violence.
Thai National Security Council secretary Anusit Kunakorn said on Wednesday Thailand had received a security warning from Singapore about three Uighurs who had entered Thailand. He did not give details.
On April 9, Thailand stepped up security because two Chinese Uighur men linked to "foreign terror groups" had overnighted on the resort island of Phuket, police said. They were later arrested in Indonesia.