Cambodian long-serving Prime Minister Hun Sen's ruling party won an absolute majority vote in the July 28 parliamentary election, according to the official results released on Sunday.

The ruling Cambodian People's Party (CPP) got 68 seats and the Cambodia National Rescue Party (CNRP) of long-time opposition leader Sam Rainsy took the remaining 55 seats, said the final results issued by the National Election Committee.

Hun Sen, 61, who has ruled the country for 28 years, will extend his power for another five years with the victory.

However, the opposition rejected the results, claiming serious irregularities during the poll. It said the party should win 63 seats, with the CPP getting 60 seats if alleged poll irregularities were fairly resolved.

On Saturday, at least 20,000 opposition supporters held a four- hour nonviolent protest at the capital's Freedom Park to reject the election results.

"We will not recognize the election results if an independent committee is not formed to investigate alleged poll irregularities, " Sam Rainsy told the rally on Saturday. "We are seeking justice for vote owners. No justice, no peace."

He also appealed to the country's King Norodom Sihamoni to help mediate a top leaders' meeting between the two parties in order to find a peaceful solution to the contested election results.

The King is currently in Beijing for routine medical checkup.

Kem Sokha, the CNRP's vice president, warned on Saturday that the party would organize another mass protest to oppose to the election results.

Security forces and armored vehicles have been deployed around the capital since early last month after the opposition threatened to call mass protests.

Under Cambodia's constitution, a new parliament will be inaugurated no later than 60 days after the election day.

Prime Minister Hun Sen has said that his party has enough lawmakers to override any opposition parliamentary boycott and form a new government.

He said, according to the constitution, a new government would be formed by a 50 percent plus one majority, or 63 lawmakers, in the new parliament.