-- Hundreds of thousands of people marched in sweltering heat and humidity through the valleys of Hong Kong's gleaming skyscrapers Thursday in a bold and spirited protest of China's refusal to expand elections in this former British colony.

Sweating through white shirts, carrying colorful banners and chanting slogans such as "Return power to the people" and "Fight for democracy," the immense but orderly crowd stretched more than two miles, from a spacious downtown park to a government building in the city's central business district.

The demonstration's main organizer, the pro-democracy Civil Human Rights Front, estimated that 530,000 people participated the procession, nearly a quarter-million more than expected. Police issued an early crowd estimate of 200,000 as people were still arriving for the demonstration, which lasted five hours on one of the hottest days of the year.

The protest was by far the largest in this city of 6.8 million since a huge anti-government rally last year attracted a crowd of more than 500,000, and leaders of the pro-democracy movement said it showed that the people of Hong Kong would not back down from their demands for universal suffrage in the face of the Chinese government's hard-line position on the matter.

"This demonstration shows the unwavering aspiration of the people for democracy," said Martin Lee, a lawmaker and former chairman of the Democratic Party who was vilified by Chinese officials earlier this year. "Even though Beijing has already said no, people are still marching."

In April, China's Communist leadership declared it would not allow Hong Kong to elect its next chief executive in 2007 or to expand legislative elections in 2008, prompting complaints it was violating the high degree of autonomy promised the city when it returned to Chinese rule seven years ago. Hong Kong's chief executive and many of its legislators are now chosen by small groups that are stacked in Beijing's favor.

"We want democracy. We want elections," said Vincent Siu, 43, a clerk at a trading company, as he marched alongside his wife and two young daughters, Gigi, 10, and Cora, 7, on one of the city's main thoroughfares. "We hope the government will listen."

China's state news media barely mentioned the demonstration, but at a news conference in Beijing, a spokeswoman for the Foreign Ministry, Zhang Qiyue, defended Hong Kong's political system, saying the territory's residents already "enjoy real and unprecedented democracy."

A few hours after the march concluded, Hong Kong's unpopular chief executive, Tung Chee-hwa, read a statement suggesting the protesters were primarily concerned about his performance and noting that the city's economy was finally recovering from a long recession.

"To those who have participated in the rally and to all my fellow citizens of Hong Kong, I clearly hear your views. I understand your aspirations," he said. But he insisted that the territory's political system should be changed only gradually and according to the limits laid out by Beijing.

The march took place on the anniversary of Hong Kong's return to Chinese rule, a public holiday. A similar march on the same date last year stunned the Chinese leadership and prompted Tung to withdraw a stringent internal security bill endorsed by the Chinese government.

This year, Tung and officials in Beijing were prepared for a large turnout, and few expect them to back down like they did last year. In recent weeks, though, several Chinese officials have taken a softer tone when speaking about Hong Kong and signaled a willingness to open a dialogue with the pro-democracy camp.

Some leading democrats in Hong Kong have responded by proposing reconciliation, and Lee and several others carried olive branches during the march. Lee said he hoped officials in Beijing would view the demonstration as an expression of the public's desire for democracy rather than a protest against the central government, and he urged the leadership to set a timetable for introducing elections in Hong Kong.

"We have to sit down and work out the road map to universal suffrage," said Jimmy Lai, publisher of Hong Kong's pro-democracy newspaper, the Apple Daily, who also carried an olive branch. "We have to get a date, and work it out with China."

But other pro-democracy activists were less conciliatory. And while protesters in last year's march focused their anger against Tung and chanted for his resignation, the target this year was the Communist leadership in Beijing. Some participants distributed flyers mocking China's influential former president, Jiang Zemin, and urging people to "Stomp on Jiang."

"We dare to say no to the ruler," Jackie Hung, spokeswoman for the Civil Human Rights Front, told a large crowd before the march began. "The ruler cannot take away our rights. We want our rights back."

Many protesters expressed anger at what they said were signs of growing interference in Hong Kong affairs by the Chinese government and efforts to intimidate the public before the march and ahead of key legislative elections in September.

Three popular radio talk-show hosts in Hong Kong who were outspoken democracy advocates quit in May, citing threats of violence and pressure from Beijing. Many people in the procession wore T-shirts with pictures of the hosts and the words, "Please come back!"

"They represent us, and they represent Hong Kong's courage," said Sandy Wang, 50, a housewife wearing one of the shirts. "We're worried about what happened to them, and what could happen to all of us. We're worried about our freedom of speech."

Special correspondent K.C. Ng contributed to this report.

A crowd that exceeded 500,000 by one estimate marches to a government building. "This demonstration shows the unwavering aspiration of the people for democracy," said Martin Lee, former chair of the Democratic Party.Tung Chee-hwa, Hong Kong's chief executive, says political change should be a gradual process.