PHNOM PENH, Cambodia -- PHNOM PENH, Cambodia (AP) — Thousands of Cambodian opposition supporters began a three-day rally Wednesday to protest what they say was a rigged election and the illegitimate return to power of Prime Minister Hun Sen.
The rally was the latest demonstration in a three-month opposition push to demand an independent probe into alleged cheating during the July 28 vote.
More than 1,000 police and soldiers were put on duty for the protest, which authorities have said they will allow as long as there is no violence. Military police spokesman Kheng Tito has said authorities will take a softer line on this rally than on one in September when clashes with police left one man dead and several injured.
Opposition leader Sam Rainsy assured the protest would be peaceful.
"We are organizing the demonstration today to find the truth and justice for the voters. We cannot bury these election irregularities by pretending we don't know about them," he said. "We are sure that there will be no violence. If there is any violence, it will not come from us."
Official election results extended Hun Sen's 28-year rule and gave his party 68 seats in parliament compared to 55 for the opposition Cambodia National Rescue Party. The CNRP says it was cheated out of victory and has boycotted the new session in parliament in protest.
On Wednesday, protesters were scheduled to march to the U.N. human rights office in Phnom Penh to deliver a petition calling for international intervention in the election dispute. The opposition says that some 2 million supporters have thumb-printed the petition addressed to the U.N. and several foreign countries.
Human Rights Watch echoed the CNRP's calls for an investigation in a statement Wednesday.
"Cambodia's donors and other countries should publicly press the Cambodian government to set up an independent, internationally assisted investigation into disputed national elections in July 2013," the New York-based rights group said.
The group's Asia director, Brad Adams, criticized France, Australia and Japan for sending congratulatory letters to Prime Minister Hun Sen, saying in the statement that "democratic leaders should skip the congratulations and instead insist on an independent investigation into malfeasance at the polls."
Associated Press writer Sopheng Cheang contributed to this report.