Riot police fired tear gas at protesters marching through a Hong Kong town to rally against suspected triad gangs who beat up pro-democracy demonstrators there last weekend.

Repeated rounds of tear gas were fired at the crowds in Yuen Long after tense standoffs with protesters, some of whom were throwing projectiles at police and had surrounded a police van.

Riot police stormed a pedestrian overpass overlooking a protest march as several thousands converged on the rural town, defying a police ban.

The police cleared all protesters from the bridge and pushed all media back to a small section, moments before tear gas was set off among the crowd.

Yuen Long is where suspected triad gang members attacked protesters and commuters at a train station last weekend.

Police, widely criticized for failing to better protect the public from the attack by club-wielding men in Yuen Long, refused to allow the march in the town on safety grounds.

But activists pushed ahead and several thousand had gathered in sweltering heat, many chanting slogans against the polic