The government of the Hong Kong Special Administrative Region has strongly condemned protesters of an illegal assembly in Yuen Long on Saturday for breaching the public peace and deliberately breaking the law, saying the police will take "serious follow-up actions".

The government deeply regrets that some people took part in a procession and a rally in the district despite objection by the police, a government spokesman said in a statement issued on early hours Sunday.

In a statement issued on Sunday morning, the police also condemned the deliberate attacks by violent protesters, stressing they will investigate all illegal and violent acts.

The condemnation came after the illegal procession in Yuen Long, western part of New Territories, ended with a bloody and violent clash between some radical protesters and police officers on Saturday night.

During nearly 7 hours of confrontation with the police, some radical protesters violently charged police's cordon lines, vandalized a police vehicle and blocked roads. They hurled bricks, threw glass bottles containing suspected corrosive fluid as well as smoke-producing material at police officers when the police were trying to disperse them.

According to the Hospital Authority, total 24 people were injured during the incident. Of them, two were in a serious condition while 16 left hospitals. At least four police officers were injured during the clash. During the operation, at least 13 men were arrested for offences including unlawful assembly, possession of offensive weapon, assaulting police officer and assault.

On Sunday morning, piles of trash were seen littered everywhere near Nam Pin Wai. Bricks, bottles, broken umbrellas, damaged fences and graffiti were also left behind, bearing the marks of the rally that occurred the previous day.

Workers in the area's public refuse collection point cleared away close to 30 bins from 7 am to 10 am on Sunday, which was double their usual workload.

Part of the exterior glass wall of a kindergarten near the Yuen Long metro station was also damaged during the protest.

"I felt heartbroken when I witnessed how the rally unfolded," said Chung, a former resident of Nam Pin Wai village in Yuen Long. The village became the site of a major standoff between riot police and protesters.

Chung has been living in Kowloon for more than a decade but returned to the village on Sunday to take pictures of the protest's aftermath.

"When I see what the village has gone through, my heart aches even more," the 70-year-old said with a trembling voice.

Amid Saturday's protest, protesters also smashed and vandalized a private car which was reportedly found with weapons inside. According to some online posts, the car was speculated to be a member of the Liaison Office of the Central People's Government in the Hong Kong Special Administrative Region.

In response to this, the department in charge of its New Territories affairs of the liaison office strongly condemned the "malicious smearing" against the office in an interview with the Hong Kong China News Agency late Saturday.

Saying the car and all belongings inside had no relations to the office or any of its staff members, the official stressed the office reserves all rights to take legal actions against those who spread the rumors.