SONGKHLA, Aug. 3 -- A Malaysian believed to be one of the leaders of a transnational human trafficking syndicate has been arrested in southern Thailand after allegedly offering "coffee money" to Immigration officers to secure the release of three Chinese nationals without valid travel documents.

The 31-year-old man, identified only as Mohammad, was detained at the Songkhla Immigration Office alongside a Vietnamese woman, Nguyen Thi Thanh, 38, Utusan Malaysia reported.

Police said the pair arrived while officers were processing the arrests of the three Chinese nationals and two Thai men detained earlier during an operation on Asian Highway 2 in Tha Chang, Bang Klam district.

Immigration Division 6 spokesman Police Colonel Charoenpong Kh...