PHNOM PENH (Reuters) - Cambodia’s opposition made significant gains in local elections against the ruling party of authoritarian Prime Minister Hun Sen on Sunday, according to the first results.

Slideshow ( 7 images )

The election for more than 1,600 communes would not mean a major shift in power, but could be a springboard for next year’s general election, in which Hun Sen aims to extend more than three decades in power in the Southeast Asian country.

The opposition Cambodia National Rescue Party (CNRP) won 11 out of the first 80 communes for which results were declared. In the last local election, the ruling Cambodian People’s Party (CPP) won 97 percent against a divided opposition.

“This is a huge success for the CNRP,” said opposition parliamentarian Yim Sovann. He told a news briefing that preliminary results from party agents showed it had won about 46 percent of the communes.

A pro-government news site gave results suggesting the opposition had won around a third of the communes.

Human rights groups had accused Hun Sen’s government of undermining democracy after his campaign warnings of violence if his party did not keep control and the arrest of some prominent critics and activists.

But no major trouble was reported on Sunday.

On his Facebook page, Hun Sen hailed the election as smooth and successful.

Transparency International Cambodia, which had more than 1,000 independent observers monitoring the poll, said it “went smoothly with little to no violence or intimidation and with most polling officials following proper procedures.”

During the Khmer Rouge regime of the 1970s some 1.8 million people died from starvation, torture, exhaustion or disease in labour camps or were bludgeoned to death during mass executions.

Since former Khmer Rouge soldier Hun Sen came to power, Cambodia has emerged from decades of conflict to clock annual growth rates above 7 percent.

But Hun Sen’s critics say corruption is widespread, and the opposition did unexpectedly well in a 2013 general election.

Cambodia’s defence minister said during the campaign that if anyone protests against the results of the election on Sunday they will be “beaten until their teeth come out”.

(Corrects ruling party name in paragraph 3 of June 4 story)