Malaysian authorities say they have discovered 139 suspected graves in a series of abandoned camps used by human traffickers on the border with Thailand where Rohingya Muslims fleeing Myanmar have been held.

Malaysian police chief Khalid Abu Bakar said that at least 28 camps were discovered along a 50-kilometer (30-mile) stretch of the Malaysian-Thai border.

He said forensics teams were exhuming the suspected graves to search for bodies.

The finding follows a similar discovery earlier this month by police in Thailand who unearthed dozens of bodies from shallow graves on the Thai side of the border. The grim discoveries are shedding new light on the hidden network of jungle camps run by traffickers, who for years held people captive while extorting ransoms from their families.