PHNOM PENH - Cambodia's opposition party claimed it had won a surprise victory in national elections Sunday, although there was no official confirmation with results yet to be announced.
"Today is a historic day as the Cambodia National Rescue Party has won the country's fifth parliamentary election," opposition leader Sam Rainsy said in a statement.
Prime Minister Hun Sen's ruling Cambodian People's Party (CPP) said it was still awaiting full results but believed it was leading the race, casting doubt on the opposition's claim.
It had 90 of the 123 seats in the previous parliament.
Rainsy thanked those who voted for his party, enabling it "to win this election", and appealed for calm before the official results.
"The CNRP would like to appeal to all compatriots to keep calm and to wait for the official results coming soon and please avoid using violence and causing trouble that would lead to chaos in society," his statement said.
"At this hour, the CPP is still leading," ruling party spokesman Khieu Kanharith told AFP.
Hun Sen has been in power for 28 years and an election defeat, if it materialised, would be a major upset.
The 60-year-old premier - who has vowed to rule until he is 74 - has traditionally enjoyed strong support in rural constituencies in particular.
Earlier the opposition decried what it described as the kingdom's worst ever poll irregularities, including missing voter names and thousands of people who turned up to find someone else had used their ballot.