Cambodian Prime Minister Hun Sen has reportedly challenged the United States to cut all aid after it announced it was ending funding for a general election next year in response to the dissolution of the main opposition party.

Key points: Prime Minister Hun Sen has cracked down on critics, rights groups and independent media

Prime Minister Hun Sen has cracked down on critics, rights groups and independent media Opposition leader, Kem Sokha has been charged with treason

Opposition leader, Kem Sokha has been charged with treason The Government accuses the Cambodia National Rescue Party of plotting a coup

Hun Sen, the strongman who has ruled Cambodia for more than three decades, has taken a strident anti-American line in an increasingly tense run-up to a 2018 election that has included a crackdown on critics, rights groups and independent media.

The United States announced on Friday it was ending funding for the election, and promised more "concrete steps", after the Supreme Court dissolved the Cambodia National Rescue Party (CNRP) at the request of the government, on the grounds it was plotting to seize power.

The party denied the accusation.

The pro-government Fresh News website reported that Hun Sen said in a speech to garment workers that he welcomed the US aid cut and urged it to cut it all.

Sorry, this video has expired Cambodian National Rescue Party's Kem Monovithya speaks to Beverley O'Connor

"Samdech Techo Hun Sen confirmed that cutting US aid won't kill the government but will only kill a group of people who serve American policies," Fresh News reported, using Hun Sen's official title.

It did not identify the people suspected of serving US policies but added: "Hun Sen … welcomes and encourages the US to cut all aid."

The US embassy in Phnom Penh did not respond to a request for comment.

In April, the US embassy announced a $US1.8 million grant to assist local elections this year and next year's general election.

The US State Department said on its website that US assistance to Cambodia for programs in health, education, governance, economic growth and clearing unexploded ordnance was worth more than $77.6 million in 2014.

Opposition leader Kem Sokha has been in jail since September. ( Reuters: Samrang Pring )

However, Chinese support for big ticket projects has allowed Hun Sen to brush off Western criticism of his crackdown on dissent.

China vastly outspends the United States in a country once destroyed by Cold War superpower rivalry, and its money goes on highly visible infrastructure projects and with no demands for political reform

In September, authorities arrested the CNRP leader, Kem Sokha, and charged him with treason over what they said was a plot to take power with US help. He denied any such plot.

The US State Department has called for Cambodia to release him and reverse the decision to ban his party.

The court also banned 118 party members from politics for five years.

Reuters