An estimated 20,000 supporters of the opposition Cambodia National Rescue Party (CNRP) took to the streets in capital Phnom Penh Sunday afternoon to call on Prime Minister Hun Sen to hold a reelection or to step down following allegations of serious irregularities during the July election.

The protests, led by CNRP President Sam Rainsy and his deputy Kem Sokha, entered the eighth day and seemed the largest-ever marching in the capital since the July election.

"We will not stop our protests if our demand is not met," Kem Sokha told the rally at the Freedom Park before starting marching. "I would like to appeal to all protesters to stick to the nonviolent principle during marching."

Sam Rainsy said "political tsunami has started in Cambodia."

Protesters, who are expected to march around 20 km through streets in the capital Sunday afternoon, waved flags and shouted in chorus "Hun Sen must step down."

Prime Minister Hun Sen said Friday that he would neither step down nor call a reelection because he has done nothing wrong.

"I have ascended to the prime minister through the constitution. If I descend, it will also be through the constitution," he said. "Therefore, I confirm that there is no reelection because no one can dissolve the National Assembly and no mechanism states about a snap election before the end of the term."

According to Article 78 of the country's constitution, the National Assembly shall not be dissolved before the end of its five-year term, except when the royal government is twice deposed within a period of twelve months.

"So, in Cambodia, the Prime Minister, the King, and the National Assembly itself have no rights to dissolve the parliament, " he said.

The premier also warned to take legal action against protesters if they blocked highways or captured government buildings.

Political row between Hun Sen's ruling party and Sam Rainsy's opposition party has persisted since the July election results showed that the ruling party won a majority of vote with 68 parliamentary seats against 55 seats for the opposition.

The opposition refused to accept the outcome and has boycotted parliament since then.

Despite the opposition's boycott, the ruling party-formed parliament voted on Sept. 24 for the establishment of a new government under the leadership of Prime Minister Hun Sen.