Thousands of pro-democracy activists dressed in black held a silent march through Hong Kong on Sunday to protest against Beijing's refusal to allow fully democratic elections when the city chooses its next leader in 2017.

Protesters carried large black cloth ribbons through the city's streets and waved banners calling for further acts of civil disobedience, Reuters reported.

Demonstrators also cheered on students planning to boycott classes and carried placards reading: "Occupy Central with Love and Peace!", "Support students boycotting classes!" and "Beijing has breached our trust! Universal suffrage is hopeless!"

Up to 4,000 demonstrators are believed to have attended the peaceful march. Police estimated that just 1,860 people turned out at the rally.

Throngs of pro-government protesters gathered nearby, hurling abuse at democracy activists and students.

Pok Chun-chung, an organiser of the pro-establishment Protect Hong Kong movement, shouted: "Students should focus on studying! If you adults have guts then you should occupy Central yourself, not use children as cannon fodder."

Democracy protests widening

Earlier on Sunday, Hong Kong's chief executive Leung Chun-ying published an open letter to residents of the special administrative region of China, urging them to be "pragmatic" and to form an "accurate and complete understanding of the constitutional and political context in which we find ourselves".

The protest is the latest in a series of pro-democracy demonstrations in which residents have voiced their anger over Beijing's involvement in Hong Kong's electoral process.

In August, thousands of people staged a demonstration in an effort to pressure Beijing to allow Hong Kong residents to have a broader choice of candidates to elect as the next chief executive.

Beijing recently announced that it will not allow fully democratic elections in 2017, and will only permit pro-Beijing candidates to stand for election.

Pro-democracy activists held an unofficial referendum, rallies and an overnight sit-in that resulted in hundreds of arrests.

Students are expected to boycott classes later this month. A sit-in in the city's central business district is also expected.

In Chinese culture, the colour black is regarded as the colour of Heaven, but it is also associated with depression and sadness.