The head of Cambodia's opposition party vowed Sunday not to give up anti-government protests despite violent police crackdowns and threats of legal action against him and his colleagues.

Cambodia National Rescue Party leader Sam Rainsy also said his party would not be baited by the violence into abandoning nonviolent tactics in its struggle to have Prime Minister Hun Sen resign and call fresh elections. The opposition claims elections in July were rigged and cheated them of victory.

The unrest is the biggest challenge in many years to the authoritarian rule of Hun Sen, who has led the country for almost three decades. Protests over the election have been generally peaceful, but a strike by workers in Cambodia's key garment sector has put extra pressure on Hun Sen's regime.

Authorities on Saturday banned rallies and street marches in the capital, Phnom Penh, and forcibly cleared about 1,000 anti-government demonstrators from a city park. Prosecutors also have issued warrants summoning Sam Rainsy and his deputy party leader to appear at a city court later this month for questioning apparently related to the current unrest.

In another example of the government's hard line, at least four people were killed Friday when police opened fire with assault rifles to break up a protest by striking garment workers demanding a doubling of the minimum wage. The labor struggle is separate from the election challenge, but unions in Cambodia have long and close ties to the opposition.

Sam Rainsy spoke Sunday at a Buddhist religious ceremony held at his party's headquarters for the four people killed in Friday's clash. About 1,000 of his supporters attended, and the meeting was uninterrupted by security forces. The party canceled its weekly rally Sunday at Freedom Park, which had been expected to draw larger than normal crowds because of public anger over Friday's shootings.

Friday's violence also caused the opposition party to cancel negotiations with Hun Sen's ruling Cambodian People's Party for a political solution to the election grievances. Sam Rainsy said talks could resume when the government stops employing threats and violence.

Sam Rainsy said Hun Sen's party had police employ force during Saturday's sweep at Freedom Park as a trap to have protesters respond in kind and discredit the opposition.

"They hoped that we would resist and refuse to move, then they would use violence, kick us and beat us and hope some of us would be angry, and would respond," he said.

Sam Rainsy said that as soon as he heard of the sweep, he told his organizers to avoid violence and move the protesters out from the site.

"We continue our peaceful and nonviolent way, so we just bypass that and then we still move forward," he said. "It will take more time, but at least we are avoiding violence."

A Phnom Penh city court prosecutor this past week issued a citation requiring Sam Rainsy and CNRP deputy leader Kem Sokha to come to court on Jan. 14 for questioning related to accusations of causing social unrest and inciting others to commit serious crimes. The prosecutor's action could lead to criminal charges being filed against them.

A copy of the citation was posted on the party's website on Saturday. Sam Rainsy said he would appear in court, and dismissed the warrant as a political tactic by Hun Sen.

Sam Rainsy returned to Cambodia from self-imposed exile shortly before July's election, after being given a pardon for charges that he said were politically inspired. His return galvanized the opposition, which made an unexpectedly strong showing in the polls even according to the official results it disputes.