Police fired tear gas and used water cannons in Admiralty after hundreds of protesters took to the streets of Hong Kong on Saturday despite a police ban and inclement weather.

The clashes started after hundreds of protesters took over a stretch of Harcourt Road, paralysing traffic, while another group moved to the protest area outside the Legco complex.

Some of the protesters threw bricks, petrol bombs and other projectiles into the government office complex and police retaliated with tear gas and water cannons.

The water jets used by the police were mixed with a blue dye, the first time this tactic has been used.

The situation soon developed into a pitched battle between protesters and police that lasted for around half an hour, with petrol bombs being thrown at officers from a bridge and police firing several rounds of tear gas.

But just before 7pm, the protesters decided to change tactic and started retreating, leaving the road empty except for an array of riot police.

The tense confrontations came after police banned marches on Hong Kong Island after rejecting an application by the Civil Human Rights Front to hold a rally to mark the fifth anniversary of a controversial edict from Beijing setting out how Hong Kong could elect its chief executive by universal suffrage.

But the ban was thrown out of the window by a group of Christians who gathered at Southorn Stadium in Wan Chai and marched to Central. Meanwhile, hundreds of people dressed in black to "shop" in the busy Causeway Bay shopping district.

Soon groups of people moved to different areas, from Wan Chai to Sheung Wan. Groups of protesters clad in black chanted slogans against the government and set up barricades as they moved from street to street with their "be water" tactics.