Prime Minister Hun Sen's ruling party was expected to win Cambodia's local elections Sunday in a vote that monitors say is tainted by vote buying and other irregularities.

The elections for local governing councils across the country are viewed as the key indicator of public opinion ahead of general elections in 2013.

Hun Sen's Cambodian People's Party has ruled Cambodia for nearly three decades. It has strong rural support and overwhelmingly won both previous local elections in 2002 and 2007.

Preliminary results from Sunday's vote were expected by Monday.

Ten political parties were vying for seats, but none has the means to compete with Hun Sen's party, said Koul Panha, executive director of election monitoring group Comfrel.

"The ruling party has used state property and civil servants to help campaign for the sake of its own party interests," he said, adding that there have also been widespread reports of vote buying and intimidation to secure support.

King Norodom Sihamoni issued a statement ahead of the election urging voters not to bow to election-related intimidation.

"I publicly call on compatriots, brothers and sisters, children, nieces and nephews not to fear oppression, intimidation or threats from any individual or political party," the constitutional monarch said in a statement issued in March.

The country's 9.2 million voters are eligible to choose councils to administer Cambodia's 1,633 communes and urban sub-districts known as sangkats.

In the 2007 commune elections, the Cambodian People's Party won 1,592 commune chief out of 1,633 communes. It was followed by the main opposition Sam Rainsy Party with 28 communes and royalist Funcinpec Party, which won two communes.