Cambodia's ruling party says it won a landslide victory in elections

Cambodia's ruling party said on Monday it had won the majority of parliamentary seats in a weekend election, as critics including the United States slammed the poll as "neither free nor fair".

The Cambodian People's Party (CPP), which ran virtually unopposed, said it won 120 out of 125 seats, cementing Prime Minister Hun Sen's grip on the country's political landscape ahead of a possible transition of power to his son Hun Manet.

"We didn't just win the election but we won it in a landslide," said CPP spokesperson Sok Eysan. "We have no option but to continue to serve the people with happiness."

The National Election Committee website on Monday showed it was still in the process of counting ballots, but did not comment on the results.

Hun Sen, 70, has ruled Cambodia for nearly four decades, with an increasingly heavy hand in recent years that has all but wiped out the opposition.

In the run-up to the election, the only meaningful opposition the Candlelight Party was disqualified from the race on a technicality, and anyone boycotting the poll was threatened with penalties.

Last week, Hun Sen signalled that Western-educated military general Hun Manet "could be" prime minister by next month.

Hun Manet, who ran for office for the first time, won a seat representing Phnom Penh in the national assembly, according to the CPP.

Pro-government Funcinpec party said it won five seats.

After Sunday's election, the US said it was pausing some foreign assistance programs in Cambodia and imposing visa bans on individuals it says undermined democracy.

State Department spokesman Matthew Miller said in a statement that Washington was "troubled" that the elections, in which Prime Minister Hun Sen's CPP faced no viable opponent were "neither free nor fair."

Miller said that ahead of voting Cambodian authorities engaged in a pattern of threats and harassment against the political opposition, media and civil society.

A group of parliamentarians from across Southeast Asia said the election was a "coronation for Hun Sen and his cronies".

"The international community must not fall into the trap of legitimising this pantomime," said Eva Kusuma Sundari of the Asean Parliamentarians for Human Rights.

About 8.1 million people voted in the one-sided election, a turnout of 84%, according to the election commission.

Many voters posted on social media images of them spoiling ballots in protest of the election. PM Hun Sen called on them to "confess" or face legal consequences.