[PENH (REUTERS)] - A Cambodian activist has been imprisoned for five years for plotting to overthrow the government, a court said on Thursday (Sept 10), bringing to 17 the number of administration opponents detained or convicted since late July.

Pen Mom, 39, was found guilty on Wednesday of conspiring with self-exiled opposition party founder Sam Rainsy to overthrow Prime Minister Hun Sen's government in 2019, the court in the southern province of Kampot said.

The jailing of Pen Mom, a former official in the disbanded Cambodia National Rescue Party (CNRP), comes during a wave of arrests of activists, which started in late July with the detention of Rong Chhun, who accused the government of ceding land to neighbouring Vietnam.

Others held include members of environmental groups Mother Nature and Khmer Thavrak, a politician, a Buddhist monk and a rapper, according to human rights group Licadho, which has been tracking arrests of dissidents and activists.

Mr Hun Sen's Cambodian People's Party (CPP) has been in power since 1979 and holds every seat in the 125-member legislature following the dissolution of the CNRP before the 2018 general election.

Ms Monovithya Kem, daughter of detained former CNRP leader Kem Sokha, said the recent crackdown showed the government's blatant abuse of the judicial system to silence dissent.

"It also shows the regime's fear of people pushing back given this unprecedented level of both political and economic turmoil," Ms Monovithya Kem told Reuters. "Our fight for democracy is far from over."

Government spokesman Phay Siphan said the administration was open to criticism and those arrested were all part of a overseas network backed by foreigners "to create social unrest and move to topple the elected government".