By DPA
Hongkong : Tens of thousands of people demonstrated here demanding democracy for Hong Kong on the 10th anniversary of its return to Chinese rule, hours after China's president warned them not to defy Beijing.
Huge crowds Sunday congregated in the city's Victoria Park, including former deputy Hong Kong leader Anson Chan, and head of the Catholic Church Cardinal Joseph Zen for the annual march to demand universal suffrage.
Early estimates put the turnout at between 40,000 and 50,000, making it the largest demonstration since the 2003 and 2004 July 1 marches which each attracted more than 500,000 people.
President Hu Jintao, visiting Hong Kong for the first time as China's leader, earlier sounded a warning to pro-democracy campaigners Sunday, warning them not to challenge Beijing's powers.
In a speech to mark the handover anniversary, President Hu spoke of the "paramount importance" of national unity above any of Hong Kong's singular interests.
But Hu left the city before the pro-democracy march began Sunday afternoon in a move that seemed designed to avoid any embarrassing confrontations.
The Chinese leader's speech, delivered at an early morning swearing-in ceremony for a new Beijing-appointed administration in Hong Kong, appeared to be a warning to campaigners pressing for universal suffrage in the former British colony.
Hu went to lengths to stress that national unity was the most important factor of the "one country, two systems" arrangement by which Hong Kong was returned to Chinese rule on July 1, 1997.
"One country and two systems cannot be separated from each other, still less should they be set against each other," Hu said.
Hu spoke of "gradual, orderly development" of Hong Kong's political system, indicating that Beijing will not be rushed into putting a date on universal suffrage in the former British colony.
Hong Kong was a British colony for 156 years before reverting to Chinese rule at the stroke of midnight on July 1, 1997, under an agreement that guarantees political freedom for 50 years.
The territory is technically entitled to full democracy from 2007 but China and Hong Kong's Beijing-appointed chief executive have so far refused to name a date for universal suffrage in the city of 6.9 million.