Residents said in a letter they wanted “to stop the forced eviction from their homes and lands.”
Aki Ra, who is 40, has been demining since 1993, without technical guidance or assistance.
Demonstrations, to be held in France, Canada and the US, will also coincide with the anniversary of the Paris Peace Agreement.
More than 100 police cleared out vendor stalls surrounding the Olympic Stadium in Phnom Penh on Friday.
In the last year, more than 120,000 Cambodian workers abroad have sent some $150 million in remittances.
In Cambodia, only a third of all chemicals in local markets are registered with the Ministry of Agriculture.
16 former staff members of the Cambodian Center for Human Rights alleges they were cheated out of their salaries and per diem payments.
The UN may be pushing for more funding at the tribunal, which has struggled financially all year.
The exploitation of resources, including for hydropower, have increased the burdens on some villagers.