Authorities have arrested the suspected bomb-maker responsible for the explosives used in a series of blasts in Bangkok last month as the city hosted a major regional summit, police said on Tuesday.
Four people were wounded when six small bombs and six incendiary devices went off on Aug 2 as Southeast Asian foreign ministers met at the summit attended by senior diplomats from world powers including China and the United States.
The suspected bomb-maker has been charged with organised crime, arson, causing explosion and illegal possession of explosives, police said.
Authorities arrested two men on the same day and have issued arrest warrants for 11 others who are still at large.
Police said all the suspects are from the country's Malay-Muslim-dominated southernmost provinces where an insurgency has killed nearly 7,000 people since 2004.
"We have issued warrants and know who they are but many have fled the country," Deputy Prime Minister Prawit Wongsuwon told reporters.
The police have said that the coordinated attacks could also be linked to political issues.