Updated

Amnesty International on Tuesday accused Cambodia's government of using its grip on the judiciary system to intimidate human rights defenders and political activists.

The London-based rights group said in a report that since the 2013 general election, longtime Prime Minister Hun Sen's government has used the courts as a tool to imprison at least 27 prominent opposition officials, human rights defenders and land activists, as well as hundreds of others facing legal cases.

"In the four years since the national election in July 2013, the country's government and the ruling Cambodian People's Party have used the criminal justice system to target activists and restrict the space they operate within," the report said.

"In Cambodia, the courts are tools in the hands of the government," Champa Patel, Amnesty International's Director for Southeast Asia and the Pacific, said in a statement. "Much lip service is paid to the judiciary's independence, but the evidence reveals a cynical manipulation of the criminal justice system to serve political goals and silence people whose views the government refuses to tolerate."

The government did not immediately respond to a request for comment.

Amnesty's criticism of the government comes as the main opposition Cambodia National Rescue Party and the ruling Cambodian People's Party campaign for Sunday's local elections.

Twelve political parties and around 88,000 commune council candidates are vying to run in 1,646 communes — or clusters of villages — throughout the country.

Although the commune elections are local affairs, the polls have the potential to have a major impact on Cambodia's political landscape for years. The next general election is set for July 2018.

Hun Sen has ruled for three decades while maintaining a framework of democracy, with violence and intimidation of opponents that continues to draw criticism. In recent weeks, he has warned of civil war if voters do not support his party, and his defense minister has reportedly warned that the army will "smash the teeth" of anyone protesting a win by the Cambodian People's Party.

In the last communal elections in 2012, Hun Sen's CPP received 60 percent of the vote, compared to the Cambodia National Rescue Party's 30.6 percent.

The opposition now says it has a better chance of winning after it nearly upset the ruling party in the 2013 general election, shaking Hun Sen's grip on power. The opposition's unexpectedly strong challenge saw it win 55 of 123 seats in the National Assembly, with Hun Sen's party reduced to 68 seats.

The Cambodian People's Party has often been accused of using violence or the threat of violence against opponents, but in recent years has stalked its foes mostly in the courts

Early this month, a U.S. State Department spokeswoman for East Asia, Alicia Edwards, said the U.S. was urging Cambodia's government to "guarantee a political space free from threats or intimidation" and respect freedom of expression for all its citizens.