Around 5,000 protesters, many waving Cambodian flags and banners, massed in a park in the capital Phnom Penh early on Sunday demanding the Prime Minister Hun Sen call a new election – the first time they have made the demand.

The opposition Cambodia National Rescue Party (CNRP) party had previously asked for an independent probe into alleged vote rigging in July polls that extended Hun Sen’s nearly three-decade rule.

Hun Sen’s government has rejected a probe, prompting the opposition to call for elections.

There was a light security presence at the lively but peaceful rally – the largest since October, according to an AFP reporter at the scene.

Ho Vann, a senior opposition member, told the crowd that the government must call “a new election as soon as possible”.

“A new election is the peaceful and democratic way forward,” Ho Vann said.

Throngs of flag-waving demonstrators, many wearing headbands reading “Long Live Democracy!” and “My Vote, My Life” chanted for Hun Sen to step down.

“We want the government to call a new election now because July’s election was marred by widespread voting fraud and there is no investigation into it so far,” protester Tep Chan Thaiya told AFP.

More people were expected to join the protest in the afternoon when opposition leaders Sam Rainsy is due to arrive to address the crowd.

Rainsy’s opposition Cambodia National Rescue Party has boycotted parliament in protest at alleged cheating in the July polls.

Rainsy has announced that he would organise daily protests.

According to official results of the July polls, the ruling Cambodian People’s Party (CPP) won 68 seats against 55 for the opposition.