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Protesters in the Cambodian capital included Buddhist monks, garment workers, farmers and supporters of the main opposition party.

PHNOM PENH, Cambodia — Tens of thousands of antigovernment demonstrators marched through Phnom Penh on Sunday in one of the biggest acts of defiance against the nearly three decades of rule by Cambodia's authoritarian prime minister, Hun Sen.

The procession, which was peaceful and stretched for several miles through a commercial district of Phnom Penh, the capital, brought together protesters with a diverse list of grievances: Buddhist monks, garment workers, farmers and supporters of the main opposition party.

They were united in their calls for Mr. Hun Sen to step down, their chants — "Hun Sen! Get Out!" — echoing down the broad avenue where they marched.

In July, Mr. Hun Sen's party claimed victory in disputed elections that the opposition and many independent monitoring organizations said were deeply flawed. Mr. Hun Sen formed a government despite the growing protests by the opposition, which has boycotted Parliament and is calling for new elections.

Cambodia's political stalemate and protest movement have been somewhat overshadowed by the turmoil in nearby Thailand, where antigovernment demonstrators are rallying to block elections and install a "people's council" to govern the country during what they describe as a hiatus from democracy.

But some analysts in Cambodia describe the past few months here as a watershed for Cambodian society, which for years has been dominated by the highly personalized rule of Mr. Hun Sen, whose party has tight control over major institutions in the country, including the army, the police, the judiciary and much of the news media.

Protesters blocking traffic and marching through downtown Phnom Penh remain a jarring sight after years during which the main message from the government has been that people should be grateful for the unity and development that Mr. Hun Sen brought to Cambodia after many years of war.

"It seems like a turning point in the history of civil society," said Yeng Virak, the executive director of the Community Legal Education Center, a Cambodian human rights organization. "People feel more free to join protests and to identify themselves as part of the opposition."

The continued vigor of the protest movement five months after the elections appears to be a reflection of the deep pool of resentment in the country toward Mr. Hun Sen.

One woman who took part in the march on Sunday, Meng Phang, 59, shouted to onlookers, including stone-face police officers, that "Hun Sen and his family are getting richer but everyone else is getting poorer."

Ms. Meng Phang's participation also represented another crucial factor of the protests: the sustained financing of the movement. Ms. Meng Phang said she had donated about $1,000 to the protest movement from money she had saved while working in a factory in Japan.

Kem Sokha, one of the protest leaders, singled out contributions "from our people abroad" in a speech to protesters on Sunday evening. There are large Cambodian populations in Australia, France and the United States, among other countries.

The grievances among protesters on Sunday were varied. Sok Heng, a middle-aged carpenter, lamented the lack of justice in the country and mentioned the case of his brother-in-law, who was killed by a thief. The police asked for a bribe before agreeing to arrest the suspect, he said.

Touch Vandeth, 24, was one of thousands of garment workers on strike, demanding a doubling of the minimum wage to $160 a month, a sharp increase that would put wages well above those of Cambodia's regional economic competitors, including Myanmar, Bangladesh and Vietnam. Ms. Touch Vandeth, who assembles Adidas footwear at a factory on the outskirts of Phnom Penh, said she had been unable to save much money on her current salary, $80 plus overtime.

Chay Soheaktra, one of the many Buddhist monks taking part in the demonstration, said he was angry that Mr. Hun Sen's government had given a forestry concession to a Vietnamese company. Anti-Vietnamese rhetoric has been a mainstay of the protest leaders, who portray Mr. Hun Sen as a puppet of Vietnam. (Mr. Hun Sen is Cambodian but came to power with the aid of an invading Vietnamese Army that pushed the Khmer Rouge from power in 1979.)

The Buddhist hierarchy is closely aligned with Mr. Hun Sen, but younger monks have joined the protests — sometimes in defiance of their elders — and are particularly angry at the theft of precious Buddhist relics this month from a Buddhist shrine. Monks question how a national treasure was so poorly guarded — especially when hundreds of security officers guard the residences of Mr. Hun Sen and other top officials.

Ou Virak, the president of the Cambodian Center for Human Rights, an independent advocacy organization in Phnom Penh, said the theft of the relics might be among the biggest problems for Mr. Hun Sen. In a country where superstition plays an important role, the theft could be taken as a supernatural sign.

Mr. Hun Sen is unpopular with a broad portion of the Cambodian electorate, Mr. Ou Virak said. But many people, especially business leaders, are not convinced that the opposition is ready to govern the country. He cited the opposition's embrace of the doubling of the minimum wage, claiming that the country could lose tens of thousands of jobs to neighboring countries.

"The majority of the people want change," Mr. Ou Virak said. "But they don't know what that change would look like."