Democrats in Hong Kong urged Chinese Vice President Xi Jinping to speed up implementation of direct elections on Sunday, during his first visit to the city since taking charge of its affairs as a state leader.

Xi, tipped as a possible future leader of the country, said he would like to gauge the changes in the former British colony which reverted to Chinese rule in 1997.

"I will do my most to walk around and see as much as I can," he told reporters. He also inspected Hong Kong's Olympic equestrian venues.

Xi made no comment on whether he would meet the city's pro-democracy legislators, who've requested talks to try to ease long-standing tensions between the two sides.

Police cordoned off roads in the city and prevented protesters from getting close.

A group of around 20 pro-democracy protesters led by radical activist-legislator Leung Kwok-hung had a heated stand-off with police in heavy rain, and were forced away from the colonial-era Government House, where Xi was to attend an evening banquet.

Hong Kong's push for direct elections has been the predominant political issue since 1997, driving a wedge between Beijing and the city's pro-democracy camp.

In December, Beijing made what was dubbed a "historic" ruling to possibly allow universal suffrage in 2017, but not in 2012 as called for by democracy advocates and a majority of Hong Kongers.

"We want to have direct elections as soon as possible and the next date is 2012," said democratic lawmaker Emily Lau, whose party marched to Beijing's Liaison office to hand in an open letter calling on Xi to respect the desire for full democracy.

Xi, charged with overseeing Beijing's final Olympics preparations, saw Hong Kong's custom-built equestrian venues.

Xi said Hong Kong authorities should "scrupulously and thoroughly perform its duty in guaranteeing the security of the events", Xinhua reported. A top Hong Kong official has said the event might by sabotaged by terrorists.

Hong Kong's Chief Secretary Henry Tang told Xi that local police would "ensure equestrian events weren't affected by political, religious or racial propaganda activities", raising the possibility that foreign activists might be barred from the city, as were several during Hong Kong's Olympic torch run.