Malaysia says it is investigating a dozen police officers suspected of being linked to human trafficking and also to recently discovered graves that are believed to contain the bodies of migrants.

Malaysian Deputy Home Minister Wan Junaidi Tuanku Jaafar made the announcement on Thursday.

He said four of the police officers had been detained as part of investigations initiated last year. No specifics were provided about the investigations, however.

The other eight officers were separately arrested for what was only generally referred to as involvement in human trafficking.

In an apparent reference to the eight officers, Junaidi said, “We will have to see whether or not there are any links to the camps. Because the arrests were made in the north (where Malaysia has borders with Thailand), we suspect there may be some connection.”

The graves and camps were found in the northern town of Wang Kelian, located near the Thailand border, on May 25.

Similar human trafficking camps were found on the Thai side of the border earlier in the month.

The discovery of 139 graves as well as the camps has triggered a crackdown on human trafficking in Malaysia. It is widely believed that the graves hold the bodies of Rohingya Muslims from Myanmar as well as Bangladeshi migrants.

A number of migrants have also been stranded at sea on cargo boats believed to be run by smugglers in the region. The international community has also been pressuring Malaysia, Thailand, and Indonesia to make efforts aimed at saving thousands of starving migrants believed to be stranded at sea.

Rohingyas have been fleeing persecution in Myanmar, where the government refuses to recognize them as citizens.

SZH/HJL/GHN