Six farmers were killed and two others injured when a landmine exploded in Cambodia's northwestern Battambang province.

Local police chief Khum Soy said the victims, whose ages ranged from 17 to 56, were "on their way home from the market when they ran over the anti-tank mine" on Sunday evening.

Police said the mine is thought to have been planted in the 1980s during fighting between the Cambodian army and Khmer Rouge rebels.

The Khmer Rouge, a communist movement that ruled Cambodia with an iron fist from 1975-79, presided over the deaths of as many as two million people through torture, execution, overwork, and starvation. Though ousted from power in 1979, the movement continued to fight government forces until the 1990s.

Cambodia is one of the most heavily mined countries in the world, a legacy of almost three decades of civil war.

In 2011, 43 people lost their lives due to landmines and other unexploded ordnance, and 168 more were injured, according to official statistics.