Seven women were arrested on Monday for blocking a main road with a bed frame to highlight flooding and poor drainage in the Boeng Kak community north of Phnom Penh.
The area is under commercial development by a consortium owned by a government senator, and residents have frequently clashed with construction workers and authorities.
Phnom Penh Municipal Court sentenced them on Tuesday to a year in prison and a fine of US$500 (Bt16,400).
Another three women and a monk were arrested on Tuesday during a rally outside the court in support of the protesters. They were jailed and fined on Wednesday for obstructing a public official with aggravating circumstances.
Both cases were processed under the provisions of “immediate appearance", where prosecutors can order an immediate trial of suspects apprehended in the act.
A group of 30 rights organisations said yesterday the swift rulings showed that “the judicial system continues to be abused in order to intimidate activists with a complete lack of accountability”.
Sok Sam Oeun, executive director of the Cambodian Defenders Project, told DPA that the fast-track procedure was legal, but so far “there are very few cases where I have seen the court use it”.