Hong Kong, Jul 27 (IANS): The Hong Kong police on Saturday fired tear gas at crowds of demonstrators rallying in the northern district of Yuen Long that has been gripped by tension following last week's assault on pro-democracy protesters by armed masked men at a railway station in the area.

Thousands of protesters marched on Saturday through Yuen Long denouncing last Sunday's assault where men -- thought to include local villagers and triad members -- armed with wooden sticks and metal rods ambushed the protesters and passers-by, leaving 45 injured.

Protesters had accused the police of turning a blind eye to the Yuen Long metro station violence and colluding with the attackers -- claims the police deny. Police officials said that 12 people have so far been arrested over the attack, including nine men with links to triads.

Amid serious concerns about public safety, the police refused permission for the march on Saturday, but the organizers vowed to proceed regardless. Tens of thousands of protesters converged in Yuen Long, chanting anti-police slogans, the South China Morning Post reported.

More than 3,000 officers were deployed to maintain order in the district and one man was slashed by another man with a blade before the protest began.

According to reports, hundreds of police in full riot gear were moving rapidly in an attempt to clear the protesters and firing multiple tear gas canisters into crowds of marchers. Many of the protesters were in masks and carrying homemade wooden shields.

Hong Kong has seen seven weeks of anti-government and pro-democracy protests. The protests were sparked by a controversial bill that would have enabled the extradition of fugitives to mainland China.

The government has since suspended the legislation - but protesters are now also demanding an inquiry into police violence, democratic reform, and the resignation of the territory's leader Carrie Lam.