Malaysian authorities have found mass graves containing the remains of more than 20 people believed to be human trafficking victims near the border with Thailand, police say.

The heavily forested Thai-Malay border has been a transit point for smugglers bringing people to South-East Asia by boat from Myanmar and Bangladesh, ABC News reported on Sunday.

The migrants are often held for ransom in squalid detention camps and, according to some accounts, face torture and starvation.

Police uncovered 24 bodies on Saturday in the Bukit Wang Burma area near the Malaysian border with Thailand, close to where authorities in May had found hundreds of bodies in illegal detention camps.