Tens of thousands of pro-democracy protesters barricaded multiple streets in Hong Kong and clashed with police officers after two weeks of relative calm in the city.

Tear gas was fired into the crowds as scores of police officers marched through the streets, after the march was declared illegal due to concerns over public safety.

Protesters responded by hurling petrol bombs at the Tsum Sha Tsui police station.

Police officers later said they seized more than 40 petrol bombs from activists.

They also detonated an explosive device, which was found rigged among broken bricks in the middle of a street.

Hong Kong protesters out in force after months of turmoil: In pictures Show all 32 1 /32 Hong Kong protesters out in force after months of turmoil: In pictures Hong Kong protesters out in force after months of turmoil: In pictures A protester throws a stone into a building at Hong Kong Polytechnic University on 11 November Reuters Hong Kong protesters out in force after months of turmoil: In pictures Police patrol the streets of Hong Kong the day after an officer shot a protester during a protest on 11 November EPA Hong Kong protesters out in force after months of turmoil: In pictures Riot police stand guard during a protest against police brutality in Hong Kong on 27 October EPA Hong Kong protesters out in force after months of turmoil: In pictures Protesters carry traffic cones to build a barricade during anti-government protests in Causeway Bay, Hong Kong on 11 November Reuters Hong Kong protesters out in force after months of turmoil: In pictures Protesters use obstacles and bricks to block a road in Hong Kong on 11 November AP Hong Kong protesters out in force after months of turmoil: In pictures Graffiti on a window smashed by student protesters in Hong Kong Polytechnic University AP Hong Kong protesters out in force after months of turmoil: In pictures Protesters carry US and British flags during a demonstration in Hong Kong on 11 November Reuters Hong Kong protesters out in force after months of turmoil: In pictures A protester throws a bottle of water as he is shrouded in tear gas during a demonstration in the Tsim Sha Tsui district of Hong Kong on 27 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures Journalists take pictures of police officers as they move to disperse protesters in Hong Kong on 27 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures An man lies injured after being attacked by protesters who suspected him of being an undercover police officer on 27 October EPA Hong Kong protesters out in force after months of turmoil: In pictures A man runs among tear gas during a protest in Hong Kong on 27 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures Protesters gather on a field in the Tsim Sha Tsui district of Hong Kong on 27 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures Pro-democracy protesters turn away from a fire lit outside the Causeway Bay Mass Rapid Transit (MTR) station in Hong Kong on 4 October Getty Hong Kong protesters out in force after months of turmoil: In pictures People rest near rows of riot police officers during a protest in Mong Kok, Hong Kong on 27 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures Pro-democracy protesters hold umbrellas as police fire tear gas at them ouside Tai Koo MTR station in Hong Kong on 3 October Getty Hong Kong protesters out in force after months of turmoil: In pictures Hong Kong police fire a water cannon from the central government office at protesters during a mass rally on the 70th anniversary of the founding of communist China on October 1 AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures Protesters burn a Chinese national flag during a mass rally on the 70th anniversary of the founding of communist China on 1 October AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures Protesters remove signs celebrating the 70th anniversary of the founding of communist China during a mass rally in Hong Kong on 1 October AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures Cardboard boxes set alight by protesters burn in the streets of Hong Kong during a mass rally on the 70th anniversary of the founding of communist China on 1 October EPA Hong Kong protesters out in force after months of turmoil: In pictures An anti-China banner has been placed in a barricade during a mass rally on the 70th anniversary of the founding of communist China on 1 October EPA Hong Kong protesters out in force after months of turmoil: In pictures A pro-democracy protester runs away after police fire a tear gas canister in Hong Kong's Wong Tai Sin district on October 4 Reuters Hong Kong protesters out in force after months of turmoil: In pictures Protesters run after police fire tear gas during a mass rally on the 70th anniversary of the founding of communist China on 4 October AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures Pro-democracy protester take cover after police fire a tear gas canister in Hong Kong's Wong Tai Sin district on 4 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures The rally comes after months of protests on the streets of Hong Kong which began in oppposition to a proposed extradition bill EPA Hong Kong protesters out in force after months of turmoil: In pictures The extradition bill would have allowed the government to extradite people to China if they were facing certain criminal charges AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures Opposition to the bill stems from the fear that the Chinese government would abuse this power for political or commercial reasons EPA Hong Kong protesters out in force after months of turmoil: In pictures Protesters soon came to demand greater freedom and universal suffrage under the One Country, Two Systems principle AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures Protesters are wearing black to symbolise opposition to China as they take to the streets in a "day of grief" while the Chinese state celebrates the 70th anniversary of its communist founding AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures A protester charges forward holding umbrellas as a mass rally breaks out in violence in Hong Kong on 1 October AFP/Getty Hong Kong protesters out in force after months of turmoil: In pictures A protester pours water on a tear gas canister fired by police during a mass rally on the 70th anniversary of the founding of communist China on 1 October Reuters Hong Kong protesters out in force after months of turmoil: In pictures A protester carries a vandalised Chinese flag through Hong Kong during a mass rally on the 70th anniversary of the founding of communist China on 1 October EPA Hong Kong protesters out in force after months of turmoil: In pictures Protesters carry a banner that denounces the celebration of the 70th anniversary of the founding of communist China on 1 October EPA

The clashes came a day after a teenage activist was stabbed and wounded while distributing leaflets near a wall with pro-democracy messages.

Police arrested a 22-year-old man in connection with the knife attack.

Hong Kong has been paralysed for months by the protests, which began over concerns that China was tightening control over the city.

“The government pretends we just want to destroy the city,” said Ray, a 24-year-old activist who did not provide his full name. “We’ll be out for as long as it takes to let the world know it is them who are destroying it.”

Hong Kong is governed under a “one country, two systems” formula, which permits the city freedoms not available on the mainland such as an independent judiciary.

Demonstrators are angry with Carrie Lam, the city’s leader, for what they see as her pro-Beijing stance.

Cheung, a 33-year-old protester, said Ms Lam was “not listening to us at all”.

She added: “This may work in China but not in Hong Kong.”

After a fortnight of relative calm, protests erupted again in the region on Saturday.

Masked protesters barricaded multiple streets, by tearing stones from the pavement and scattering them on the road. Crowds also used plastic safety barriers and metal railings to form the makeshift barricades.

They also trashed hundreds of shops during the march, including a discount grocery chain, which they said were under pro-Beijing ownership. They also tried to set fire to metro stations and branches of Chinese banks, setting off sprinklers in two.

Many demonstrators covered their faces in defiance of a new law barring them from wearing masks. They also sang the protest movement’s anthem and held up placards which depicted China‘s flag as a Nazi swastika.

The Civil Human Rights Front, which organised the march despite not obtaining police approval, said around 350,000 protesters took part.

“You can see Hong Kongers won’t easily give up their right to demonstrate. Today’s turnout is more than I expected,” said Daniel Yeung, one of the activists taking part.

“You can see that as long as people keep coming out in large numbers we are safe and can keep fighting,” he added.

Police deployed several water cannon trucks to spray jets of blue-dye at protesters, which they use to identify demonstrators. Many people hit by the liquid also developed coughs, suggesting an irritant may be mixed with the water.

One water cannon sprayed a mosque in Kolwoon, an area in the city’s north, covering the building in blue liquid.

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Residents jeered at riot police marching in the streets. Officers, in turn, told the people they were part of an illegal assembly.

As night fell the crowds set rubbish on fire in the middle of several streets and officers responded by firing yet more tear gas.

The crowds have five core demands: universal suffrage, an independent inquiry into police action against protesters, amnesty for those charged, an end to describing protesters as rioters, and the formal withdrawal of a controversial bill allowing the extradition of prisoners to mainland China.

The bill triggered the protests earlier this summer. Ms Lam has declared the legislation abandoned but it is yet to be formally withdrawn.

She has rejected the other demands and on Sunday she said a police complaints inquiry will be completed before the end of the year.

Two people have been shot and wounded by police and thousands have been injured since the protests escalated in June.