Kampong Chhnang provincial court ordered two people to eight months in prison Thursday, and a third in absentia, finding they had ignored a court order to stay off a tract of private land.
The courts sentenced the two, one man, Sar Song, and one woman, Oun Thum, despite the protests of about 150 people outside the court, who demanded their release.
A third man, Yuos To, was sentenced to eight months in absentia.
The sentences stemmed from a lawsuit by a private company that claimed the three refused to stop living on company land.
Protestors told VOA Khmer by phone Thursday they believed the courts and local officials had been paid off by the local company, known by its initials, KDC, to push them off their land.
Srei Aun, daughter of Oun Thum, called the courts "unjust."
"People who have made no mistake are sentenced to jail, and people who have made mistakes are not punished," she said.
She accused Commune Chief Dy Doeurn of colluding with KDC to oust people from the land.
Dy Doeurn said Thursday he had no relationship with the company. KDC could not be reached for comment.
Sao Pheareak, a rights investigator for Licadho, who monitored the hearing and protest this morning, said the court's decision was unfair.
"As I see it, the company never owned that land," he said.
Provincial Judge Veng Huk dismissed accusations of injustice, telling VOA Khmer by phone Thursday he had made his decision based on the law.
"We already examined the case and saw that those three people grabbed the land of the others, who paid for the official letter of property ownership," he said.
The protestors fired stones from slingshots at military police, injuring one officer, Veng Huk added.
The protestors represented about 108 families who lost their land in a dispute with KDC that has lasted since 2006 and where both sides have accused the other of land theft.