The leader of the dissolved Cambodian National Rescue Party made the call in a New Year's message read out by his daughter in a Facebook video. The CNRP was disbanded after being accused of planning a coup.
Jailed Cambodian opposition leader Kem Sokha called for free and fair elections in the Southeast Asian nation in a New Year's message on Monday.
"Leave an opportunity for people to choose leadership representatives through an election that is free and fair," Kem Sokha said in the letter, read out by his daughter in a video posted on his Facebook page.
Kem Sokha said 2017 had been marked by big political crises that led to a "democracy walked backward."
The leader of the dissolved Cambodian National Rescue Party (CNRP) was charged with treason for allegedly conspiring with the United States to topple the Cambodian government and could face up to 30 years in prison if convicted.
He was arrested in September on the basis of videos from several years ago showing him at a seminar where he spoke about receiving advice from US pro-democracy groups.
Read more: Is Cambodia an autocratic state now?
A spokesman from the ruling Cambodian People's Party (CPP), Sok Eysan, told Reuters news agency there was little interest in Kem Sokha's New Year's message and that opposition politicians were free to create a new party.
The Cambodian election is set to take place next year on July 29. Prime Minister Hun Sen has vowed to extend his reign by at least another decade.
A tumultuous year
Kem Sokha's message comes following what has been a tumultuous year for Cambodia. The country is experiencing an ongoing crackdown by the CPP on critics, civil society groups and independent media.
Cambodia's Supreme Court dissolved the CNRP in November and banned more than 100 opposition lawmakers from politics after Hun Sen accused the party of planning a coup in the country.
The CNRP had been seen as the only viable contender in the upcoming election.
The court's decision prompted the European Union and the United States to withdraw their support of the 2018 election, but China – Cambodia's biggest donor – last week announced it would assist the country.
Hun Sen has also called for the closure of the Cambodian Center for Human Rights, founded by Kem Sokha. "The Cambodian Center for Human Rights must be shut down because it was created by foreigners, not Cambodians," Hun Sen told the Phnom Penh Post.
A crackdown on local media saw the Cambodia Daily, an English-language national newspaper, closed down in September after authorities gave it one month to pay $6.3 million (5.3 million euros) for years of back taxes.
Last week, two journalists from US-funded Radio Free Asia who had been charged with espionage in November were denied bail.
Most recently, a Phnom Penh court on Friday ordered former CNRP leader Sam Rainsy to pay Hun Sen $1 million in damages for defamation because of a Facebook post in January in which he accused the prime minister of offering $1 million to a political operative to attack the opposition.
law/tj (dpa, Reuters)