Police said nine people were arrested under the law, including a man with a Hong Kong independence flag and a woman holding a sign displaying the British flag and calling for Hong Kong''s independence.
Others were detained for possessing items advocating independence. Further details were not immediately available.
Hong Kong police said on Facebook that they arrested more than 300 people on various charges, including unlawful assembly, possession of weapons and violating the national security law.
The arrests come as thousands took to the streets Wednesday on the 23rd anniversary of Britain''s handover of Hong Kong to China in 1997. For the first time, police banned this year''s annual march. Protesters shouted slogans, lambasted police and held up signs condemning the Chinese government and the new security law.
The new security law deepened concerns in Hong Kong and abroad about the semi-autonomous territory''s future.
The law, imposed by China following anti-government protests in Hong Kong last year, makes secessionist, subversive, or terrorist activities illegal, as well as foreign intervention in the city''s internal affairs.
Any person taking part in secessionist activities, such as shouting slogans or holding up banners and flags calling for the city''s independence, is violating the law regardless of whether violence is used.
The most serious offenders, such as those deemed to be masterminds behind the crimes, could receive a maximum punishment of life imprisonment. Lesser offenders could receive jail terms of up to three years, short-term detention or restriction.
Hong Kong''s leader strongly endorsed the new law in a speech marking Wednesday''s 23rd anniversary of the handover of the territory — officially called the Hong Kong Special Administrative Region — from British colonial rule.
“The enactment of the national law is regarded as the most significant development in the relationship between the central authorities and the HKSAR since Hong Kong''s return to the motherland,” chief executive Carrie Lam said in a speech, following a flag-raising ceremony and the playing of China''s national anthem.
“It is also an essential and timely decision for restoring stability in Hong Kong,” she said. A pro-democracy political party, The League of Social Democrats, organized a protest march during the flag-raising ceremony. About a dozen participants chanted slogans echoing demands from protesters last year for political reform and an investigation into accusations of police abuse.
The law''s passage Tuesday further blurs the distinction between the legal systems of Hong Kong, which maintained aspects of British law after the 1997 handover, and the mainland''s authoritarian Communist Party system.
Critics say the law effectively ends the “one country, two systems” framework under which Hong Kong was promised a high degree of autonomy.
The law directly targets some of the actions of anti-government protesters last year, which included attacks on government offices and police stations, damage to subway stations and the shutdown of the city''s international airport.
Acts of vandalism against government facilities or public transit can be prosecuted as subversion or terrorism, while anyone taking part in activities deemed secessionist would also be in violation of the law.
Pro-democracy lawmaker Claudia Mo said in a news conference that the security legislation does not follow the rule of law and is a dire warning to the free press.
“This would tell you that they want not just to get us, but to intimidate us into inaction, into a catatonic state,” Mo said.
Hong Kong''s police force said they would consider as illegal any flag or banner raised by protesters deemed to promote Hong Kong''s separation from China or express support for independence for Tibet, Xinjiang or the self-governing island democracy of Taiwan that China claims as its own.
Police will use a new purple flag to warn protesters if they display banners or shout slogans that may constitute a crime under the law.
Schools, social groups, media outlets, websites and others will be monitored and their national security awareness will be raised, according to the law, while the central government will have authority over the activities of foreign non-governmental organizations and media outlets in Hong Kong.
The law says central government bodies in Hong Kong will take over in “complicated cases” and when there is a serious threat to national security. Local authorities are barred from interfering with central government bodies operating in Hong Kong while they are carrying out their duties.
Security legislation was mandated under Hong Kong''s local constitution, but an earlier attempt to pass it in the city''s legislative body in 2003 was shelved because of massive public opposition.
Beijing finally decided to circumvent the Hong Kong legislature and have the law passed Tuesday by the Standing Committee of the National People''s Congress, China''s rubber-stamp parliament.
President Xi Jinping signed a presidential order putting the law into effect, and it has been added to the Basic Law, Hong Kong''s constitution. (AP)
Disclaimer :- This story has not been edited by Outlook staff and is auto-generated from news agency feeds. Source: PTI