More than 30 people were arrested on charges of violating the law on the first day of the Hong Kong National Security Law.

Hong Kong police say they have arrested more than 30 people in the Causeway Bay area at noon on charges of illegal gatherings, violations of the Hong Kong Security Law, interference with police officials, and possession of offensive weapons.

Today (1st) is the 23rd anniversary of Hong Kong's sovereignty return from England to China.

Despite police disapproval, protests were held throughout Hong Kong against Hong Kong's security law.

Among the arrests were opposition lawmakers Raymond Chan and Tam Tak Chi, Hong Kong Media South China Morning Post reported.

Water cannons and police armored vehicles are prominent in downtown Hong Kong, such as Wan Chai, and police boundaries are tight, the newspaper said.

Police also reportedly used water cannons and pepper sprays.

The first case arrested for violating the Hong Kong Security Law was a man in the Causeway Bay area carrying a flag saying'Hong Kong Independence'.

Police have also raised flags to warn protesters that intentions such as independence and overthrow towards the protesters and spreading flags or shouting slogans could violate Hong Kong security laws.

Hong Kong's chief executive, Carrie Lam, said at a press conference that most Hong Kong governments would do their best to apply the law, except in exceptional circumstances.

Hong Kong Security Minister John Lee also warned protesters against testing Hong Kong security laws.

The Hong Kong Security Law includes the prohibition and punishment of foreign forces and collusions, national divisions, the overthrow of state government, and terrorism, and the establishment of an agency in Hong Kong to enforce them.

Yesterday, after passing the Commerce Committee of the National People's Congress of China, it was incorporated into the Hong Kong Subconstitution's Basic Law Supplement, which came into effect later this afternoon. 

(Photo = AP, Yonhap News)