Cambodia's prime minister has established a special commission to investigate the long-unsolved killings of three labor leaders.

It was unclear why Prime Minister Hun Sen would revive the murder cases, which sparked international accusations of impunity for human rights abuses under his government — a concern that remains today. Hun Sen has led Cambodia since 1985 with a combination of guile, threat and violence, though in recent years he has tried to establish himself as regional statesman.

A directive circulated Thursday orders several government ministries to probe the murders of Chea Vichea and Ros Sovannarith in 2004 and Hy Vuthy in 2007.

Chea Vichea's brother Chea Muny said he doubted justice would be achieved by the commission because it has no members from outside government.