Hun Sen ordered officials to visit contested areas and issue deeds to families facing illegal evictions, a move he said would bring "harmony" to the country, amid growing criticism of Cambodia's handling of the problem.

"I say it must be done in six months at the latest," Hun Sen said in a speech broadcast on television, denying the move was a ploy to woo voters ahead of next year's general election.

The strongman premier did not specify how his order would help those who have already lost their homes and land to make way for private developments, and rights groups immediately cast doubt over the sincerity of his vow to resolve the issue.

"The government has made numerous orders regarding land concessions, including pledges to suspend new concessions, review prior concessions and revoke concessions from companies using armed forces," Naly Pilorge, director of local human rights group Licadho, told AFP.

"None of these orders have been enforced. This doesn't bode well for the enforcement of the latest public instruction."

Campaigners have accused the government of granting swathes of land to well-connected firms in recent years, ignoring villagers' land rights and displacing tens of thousands of people.

Protests have intensified in recent months, leading to a number of arrests and clashes between residents and security forces.

In one of the worst incidents to date, a 14-year-old girl was shot dead last month when armed government forces fought with villagers resisting an alleged land grab in eastern Kratie province.

"I regret the death of the girl," Hun Sen said.

More recently, 13 female land rights activists were jailed after a three-hour trial widely condemned as unjust, prompting US Secretary of State Hillary Clinton to call for their release.

Land titles are a murky issue in Cambodia where private ownership was abolished during the 1975-1979 rule of the communist Khmer Rouge and many legal documents were lost.