Villagers in north-western Cambodia have unearthed what authorities say could be a mass grave from the Khmer Rouge era which contains skulls and skeletons - some with their legs bound by rope.

The morbid discovery was made last weekend about 60km from Siem Reap, home to Cambodia's famed Angkor Wat temples.

Authorities said today that villagers were excavating land in a forested area when they discovered about 20 skulls and other bones.

Nhim Sela, a Siem Reap military official, said the remains were found at the site of a former Khmer Rouge prison where hundreds were believed to have been killed.

Soldiers were assigned to guard the site while authorities discussed whether to dig deeper.

An estimated 1.7 million people were killed during the regime's 1970s rule.