Two demonstrations—one of factory workers and one of displaced city residents—were held on Monday.
Security forces have left a village in Kratie that was the site of the shooting death of a teenage girl by government forces last week.
The delegation also met with UN officials in New York last week and were scheduled to talk with the US State Department Friday.
Those arrested were Khat Sovann, 54, Pum Vannak, 53, Pon Soeurn, 34, and an unnamed fourth suspect.
Rights workers estimated between 400 and 1,000 villagers in Broma village, Chlong district, were set to be evicted.
Family members say Chan Samnang died because of exposure to poor living conditions at a relocation site outside the city.
Villagers say they have been pushed off nearly 1,500 hectares of land to make way for the senator’s sugar cane crops.
The country had nearly 450,000 Internet users at the end of 2011, according to the Internet World Stats website.
Joel Brinkley, a professor of journalism, spoke to VOA Khmer recently about his book and possible solutions to Cambodia’s “curse.”
An estimated 2.3 million hectares were given over as concessions to private companies in recent years, Adhoc recently reported.
The 27-minute film follows the work of a leading NGO working to rally support for an end to widespread land grabbing in Cambodia.
A United Nations-appointed rights watchdog is calling on Cambodia to bridge the widening gap between the rich and the poor.