The Supreme Court of Cambodia has dissolved the Cambodia National Rescue Party (CNRP), the most popular opposition party in the country.

The ruling on Thursday, which was delivered by a judge who is also a member of the ruling Cambodian People's Party (CPP), barred 118 members of the opposition from politics for five years.

"Today marks the end of true democracy in Cambodia," said CNRP Vice President Mu Sochua, who fled Cambodia in early October.

The decision was seen as predetermined, with Cambodian Prime Minister Hun Sen saying on Wednesday "I dare to bet my life" on the CNRP being outlawed.

Sen publicly encouraged CNRP legislators to defect to his party before the Supreme Court announced its decision.

The dissolution of the main opposition party is being seen as an end to Cambodia's democracy.

'Immediate steps to reverse course'

"Dissolving the main opposition party, coupled with a heavy-handed crackdown on the media and civil society, certainly looks like the move of a dictator - a frightened one," said Charles Santiago, a member of the Malaysian Parliament and chair of ASEAN Parliamentarians for Human Rights.

"Cambodia's future now depends on whether the ruling party is prepared to take immediate steps to reverse course."

A large perimeter surrounding the Supreme Court in the capital Phnom Penh has been sealed off by patrolling police and military.

A reporter in Phnom Penh, who asked to remain nameless for safety concerns, told Al Jazeera he had never seen such a heavy police presence in the capital, where he had lived for roughly a decade.

The decision is the latest in a series of moves against the main opposition party.

Kem Sokha, leader of the CNRP, was jailed in early September on charges of treason. Cambodian authorities allege Sokha colluded with the US to topple the government.

The charge comes from a 2013 video during which Sokha allegedly says the US assisted in planning his political career. The charge carries a sentence of 15 to 30 years.

Former CNRP leader Sam Rainsy fled to France in 2016 after being charged with defamation for accusing the Sen administration of planning the death of prominent political commentator and activist Kem Ley.

Rainsy was convicted of defamation that same year and the Supreme Court upheld the conviction earlier this month.