By Robert Walker
BBC World Service
Ramon Fil says he was tricked into signing away more land
Romam Fil is moving rapidly through a dense patch of forest. Every few metres he pauses and points to edible plants and roots that the Jarai people of north eastern Cambodia have relied on for generations.
Then suddenly the trees come to an end. In front of us is a vast clearing, the red earth churned up and dotted with tree stumps.
Beyond that, stretching as far as we can see is a rubber plantation, the young trees are still thin and spindly and sway gently in the breeze.
This is the scene of a battle the Jarai people of Kong Yu village have been fighting, and losing for the past five years.
It started when local officials called a meeting and said they needed some of the forest.
"They told us they wanted to give part of our land to disabled soldiers," said Mr Fil.
"They said if you don't give us the land, we'll take it. So we agreed to give them a small area, just 50 hectares."
The villagers say they were then invited to a party and when many of them were drunk they were asked to put their thumbprints on documents.
"Most of us don't know how to read or write, and the chiefs did not explain what the thumbprints were for," said Mr Fil.
The villagers later found they had signed away more than 400 hectares - and the land was not for disabled soldiers, but a private company who began making way for the rubber plantation.
"They cleared areas where our people had their farms, and they destroyed our burial ground," said Mr Fil.
Lawyers for the owner of the plantation company, a powerful businesswoman called Keat Kolney, insist she bought the land legally.
The Cambodian government has been accused of undermining the poor
But groups advocating for local land rights in Cambodia say part of the reason she was able to acquire the land is because she is married to a senior official in the ministry of land management.
It is not the only case where those closely connected to senior government figures are alleged to have taken land from poor Cambodians.
Five years ago, in north-western Pursat province a large grazing area was turned into an economic land concession - land the government grants to private firms for investment in large-scale agriculture.
It was allocated to a politically well-connected company called Pheapimex.
"They just came one day with their bulldozers and started clearing the land straight away," said Chamran, a farmer in the area.
"So we organised a demonstration but then a grenade was thrown among us - we don't know who by. Nine people were injured. The military police pointed a gun in my stomach and said if you hold another demonstration we will kill you."
Under the law, land concessions granted by the government should not exceed 10,000 hectares but the Pheapimex concession, although much of it is so far inactive, covers 300,000 hectares.
Global Witness, an environmental pressure group, estimates Pheapimex now controls 7% of Cambodia's land area.
The organisation says the company's owners, a prominent senator and his wife, have strong links to Cambodian Prime Minister Hun Sen.
Pheapimex did not reply to requests for a response to these allegations, but the Cambodian government maintains that the process by which private companies acquire land is both transparent and legal.
"The requirement is not to be close to the prime minister," said Phay Siphan, spokesman for Cambodia's Council of Ministers.
"The requirement is that you have enough capital, you have the technology to develop the land."
It is not just in rural areas that people complain of losing land.
Cambodia's recent stability, following decades of violence, has attracted a rapid boom in tourism and a race among foreign and local entrepreneurs for prime real estate on which to build new resorts.
Farmers have been threatened with jail if they demonstrate
Many of the country's beaches have already been bought up.
And rights groups estimate that 30,000 people have been forcibly evicted from their homes in the capital Phnom Penh over the past five years to make way for new developments.
The roots of the problem date back to the 1970s when the brutal Khmer Rouge regime abolished private property and destroyed many title documents.
A land law passed in 2001 recognises the rights of people who have lived on land without dispute for five years or more, but in many cases it is not being implemented.
The UN estimates hundreds of thousands of Cambodians are now affected by land disputes.
The government has said that they are not forcefully taking land from farmers
But land is not the only state asset being sold at an alarming rate.
Beginning in the 1990s, large swathes of the country's rich forests were bought up by logging companies.
Now sizeable mining and gas concessions are also being granted to private enterprises.
Eleanor Nichol of Global Witness believes individual members of the Cambodian government, right up to the highest levels, are benefiting.
"Essentially what we're dealing with here is a kleptocratic state which is using the country and its assets as their own personal slush fund," she said.
The Cambodian government rejects these allegations.
"They could accuse [the government of] anything they like. Cambodia operates under a modernised state of law. Everyone is together under one law, said Phay Siphan.
Back in Kong Yu village, the Jarai people are waiting to hear the result of suit filed in a local court to try to get their land back.
"If the company gets the land, many of our people will starve," says Mr Fil.
"If we lose the land, we have lost everything.
Assignment is broadcast on BBC World Service on Thursday at 0906 GMT and repeated at 1406 GMT, 1906 GMT, 2306 GMT and on Saturday at 1106 GMT.
You can listen
or download the