Police were seeking court arrest warrants for three suspects in the Bangkok bombings believed to have plotted the attack in a neighbouring country and to have since returned there, Deputy Prime Minister Prawit Wongsuwon said on Wednesday.
Gen Prawit said the Aug 2 bombings in Bangkok and Nonthaburi province were planned in a neighbouring country. The three men were actively involved in the bombings and had then fled back to the neighbouring country.
Police were contacting their counterparts across the border, seeking the fugitives' apprehension, Gen Prawit said at Government House. He did not name the neighbouring country.
Police have linked the attacks to the insurgency in the Muslim-majority far South. A police source said the attacks were planned at a meeting held near the Thai-Malaysian border.
Geb Prawit said police were making progress in their investigation.
Two detained suspects in the bombings were brought to Bangkok from Narathiwat on Tuesday. They were identified as Lu-ai Sae-ngae, 23, and Widan Maha, 29. Mr Lu-ai was being held at the Pathumwan police station and Mr Widan at Bang Rak police station.
Police were authorised to detain suspects for 48 hours. The Metropolitan Police Bureau would on Thursday ask the Bangkok South Criminal Court to extend their detention.
Both suspects were charged with organised crime, illegal possession of explosives, attempted murder and carrying explosives. he said. A total of 15 suspects were believed to be involved in the bombings.
The two men are accused of planting two bombs, which authorities initially said were dummy devices, in front of police headquarters in Bangkok on Aug 1, the day before the blasts.
A security camera recorded one of the two men dropping a plastic bag near the fence outside the Royal Thai Police Office on Rama I Road on the evening of Aug 1.
In the bag was a time-bomb set to go off at 8am on Aug 2. It was defused by bomb disposal officers.
Six bombs and six incendiary devices detonated on Aug 2, as the city hosted the Asean Foreign Ministers Meeting, which was also attended by diplomats from the United States, China and other world powers.
The explosions occurred at Chong Nonsi BTS station near the King Power Mahanakhon building, the Government Complex on Chaeng Watthana Road, and the Royal Thai Armed Forces Headquarters, and the Office of the Permanent Secretary for Defence in Nonthaburi's Pak Kret district. They injured five people.