Thai Prime Minister Prayuth Chan-ocha told reporters in Bangkok on Tuesday that the suspect had been taken into custody as he attempted to cross into Cambodia from Thailand.

"He has been arrested at Sa Kaeo checkpoint," Prayuth said, referring to the Thai side of a border crossing.

Prayuth, who is also the leader of the junta that runs Thailand, did not confirm that the suspect taken into custody was thought to be the person who planted the bomb that went off at the Erawan shrine in Bangkok's busy Chidlom shopping district on August 17.

"We are interrogating," Prayuth said in response to a reporter's question. "He is a main suspect and a foreigner."

The prime minister added that investigators had learned that suspects were seeking to leave the country, and that they had traced this particular suspect to the Sa Kaeo crossing point.

Motive remains unclear

Almost a fortnight after the bombing the motive remains a mystery, and Prayuth said he hoped the interrogation of the main suspect would go a long way to helping police connect the dots of the case.

Security officials have already been interrogating a man arrested on Saturday during a raid on a Bangkok flat where bomb-making equipment was recovered. Officials say that suspect has been linked to the bombing, but they have not yet identified him or his nationality.

On Monday, arrest warrants were issued for two more suspects, a Thai woman and a foreign man.

pfd/kms (AFP, AP, Reuters, dpa)