Cambodians Vote In "Sham" National Election

With the main opposition silenced, Cambodians are voting in an election virtually certain to return to office Prime Minister Hun Sen and his party.

Although 20 parties are contesting the polls on Sunday, the only one with the popularity and organisation to mount a credible challenge, the Cambodian National Rescue Party, was dissolved last year by the Supreme Court. Its leaders have called on supporters to boycott the polls, charging they are neither fair nor free.

Along with fracturing the political opposition, Hun Sen's government also silenced critical voices in the media and ahead of the polls, ordered the temporary blocking of 17 websites, citing regulations prohibiting media from disseminating information that might affect security. The blocked websites included those of the US government-funded Voice of America as well as local media.

Hun Sen, whose 33 years in power makes him the world's longest serving national leader, promised peace and prosperity at a rally on the last day of campaigning on Friday, but attacked the opposition's boycott call and called those who heed it "destroyers of democracy".

Hun Sen and his wife cast their ballots south of the capital shortly after polling stations opened.

Cambodian Prime Minister Hun Sen has been in power for three decades. Image: AAP

His ruling Cambodian People's Party was alarmed by the last general election in 2013, when the race was close enough for the opposition to claim that it would have won except for manipulation of the voter registration process. Hun Sen, 65, said that he intends to stay in power for at least two more five-year terms.

He was a member of the radical communist Khmer Rouge during its successful five-year war to topple a pro-American government, then defected to Vietnam during Khmer Rouge leader Pol Pot's 1975-79 genocidal regime that left nearly 2 million dead.

He became prime minister in 1985 in a Vietnamese-backed single-party communist government and led Cambodia through a civil war against the Khmer Rouge, which eased off with the 1991 Paris Peace Accords that also installed a democratic political framework.

Exiled opposition leader Sam Rainsy made a final appeal to Cambodians by urging them not to vote. On his Facebook page, he said that the sham election was destroying Cambodia's future and called Hun Sen a "real traitor."

Hun Sen on Saturday met with foreign election observers, including those from Russia, China and Indonesia. The US, the EU and Japan declined to send poll watchers, saying the election was not credible.