Protesters and police have clashed in Hong Kong in another weekend of unrest as tensions escalate in the run-up to a significant political anniversary for Beijing.

Riot police fired teargas, pepper spray and bean bag rounds on protesters who vandalised metro stations and set improvised barricades ablaze in several flashpoints across the city.

The confrontations mark the 16th consecutive weekend of mass protest for the semi-autonomous Chinese territory and come less than 10 days before China celebrates its national day on 1 October, the 70th anniversary of the founding of the People’s Republic of China.

Facebook Twitter Pinterest Protesters deface a Chinese flag at the New Town Plaza shopping mall in Hong Kong’s Sha Tin district. Photograph: Isaac Lawrence/AFP/Getty Images

Earlier, residents had staged a peaceful rally at the New Town Plaza in Sha Tin, a key site of protests after police stormed the mall and clashed with protesters there in July. Demonstrators decorated the mall with origami paper cranes and hung banners from the railings. A small group of musicians wearing masks played the song Glory to Hong Kong, which has become the anthem of the protests.

Scenes at the mall turned ugly as protesters surrounded a man and accused him of being a spy from mainland China and punched and kicked him. Video footage showed the man walking away from the group, bleeding from the head.

Protesters at the mall trampled on the Chinese flag and painted it black before dumping it into a river while crowds gathered outside the mall, hurling bricks from an overpass at riot police who fired multiple rounds of teargas at them.

Riot police fire teargas at Hong Kong protesters as unrest escalates Read more

Police also fired on demonstrators who gathered in the early evening in Mong Kok, in Kowloon, a frequent site of clashes between police and protesters during the last three months. The police said in a statement that “radical protesters” had thrown bricks at the local police station and set fires at road junctions, “endangering the safety of everyone at scene and seriously affecting traffic nearby”.

Elsewhere, protesters unfurled a large banner with the words “Glory to Hong Kong” and residents supportive of the protesters came out to the streets to heckle police. In one incident, a police officer charged at residents gathered in Kawi Fong in northern Hong Kong, with his baton raised, before a colleague pulled him back.

Protesters vandalised metro stations, smashing CCTV cameras and spray painting ticket machines. Protesters have begun to target Hong Kong’s Mass Transit Railway after the operator was seen as bowing to government pressure to close stations during protests, making it harder for demonstrators to escape or for others to join.

Facebook Twitter Pinterest A child arranges origami cranes in the pro-democracy rally at a Sha Tin shopping mall on Sunday. Photograph: Kin Cheung/AP

Demonstrators have also been calling on the rail operator to release CCTV footage of arrests made on 31 August at the Prince Edward station in Kowloon believed to have turned violent.

In the late evening, protesters and crowds of supporters and bystanders continued to gather in Mong Kok in Kowloon, jeering at rows of riot police. Cars drove by beeping in support, prompting cheers from the crowd, which began chanting “stand for freedom, stand with Hong Kong”.

As the 1 October holiday approaches, Beijing has put extensive security measures in place. Authorities are keen not to let any incident mar the day, which will be marked by a massive military parade and a speech by Chinese president Xi Jinping.

Hong Kong’s chief executive, Carrie Lam, said she would formally withdraw a controversial extradition bill that triggered the protests in June. But over the course of protests and clashes, the demands of demonstrators have expanded to include an independent inquiry into police behaviour as well as implementing universal suffrage.

Protesters say the city’s freedoms, including independent courts, press, and rule of law, have been eroded since the former British colony was handed over to Beijing in 1997, under an agreement that promised Hong Kong a “high degree of autonomy” for 50 years.

Hong Kong has cancelled fireworks originally scheduled for the day, and the police appear to be cracking down harder, adding to the more than 1,400 people arrested since June. Last week, Amnesty International released a report based on interviews, showing a “disturbing pattern” of arbitrary arrests and “retaliatory violence”.

Police said they had arrested two 13-year-olds at protests on Saturday, one of whom was accused of burning the Chinese flag. Offenders are liable to a fine and imprisonment for up to three years. Under Hong Kong law, offenders under the age of 14 cannot be sentenced to prison.

Speaking at a reception for the 70th anniversary, Lam said her government would spare no effort in stopping the violence.