The main suspect in the deadly Bangkok blast, who was seen in CCTV footage wearing a yellow T-shirt, has been arrested, Thailand's Prime Minister Prayut Chan-o-cha reportedly said on Tuesday.

The suspect, said to be a foreigner, was arrested while trying to cross the border into Cambodia at Ban Pa Rai in Aranyaprathet district, Bangkok Post reported. 

"He is a main suspect and a foreigner," the Thailand PM reportedly said. 

The suspect was seen in a CCTV footage leaving a backpack near the Erawan Shrine in Bangkok's busy tourist area on 17 August. 

The blast had killed 20 people, including several foreigners.

The Bangkok police had earlier arrested another suspect on Saturday and had also recovered some explosive material from his apartment in the city.