The Hong Kong Special Administrative Region government said on Monday it has banned a separatist group that advocates "Hong Kong independence".

SAR Secretary for Security John Lee Ka-chiu, who made the decision, said the ban on the "Hong Kong National Party" was in accordance with the Societies Ordinance.

The ban on the HKNP, effective immediately, was made in the interests of national security, public safety, public order and the protection of the rights and freedoms of others, Lee said.

What the HKNP aims to do contravenes the Basic Law and undermines national security, the security chief said.

The secretary for security is vested with the power to issue an order to prohibit the operation or continued operation of a society if it violates stipulations in the Societies Ordinance.

To achieve its goal of splitting Hong Kong from the country, the HKNP has repeatedly called for the "use of all means", including using "force", and has encouraged its supporters to use force, in various social media posts and public statements, the government said.

The ban came after police had given the group about two months, until Sept 14, to submit arguments against the proposed ban. The police extended the deadline three times at the HKNP's request for more time to seek legal advice.

Defying the proposed ban issued on July 17, the HKNP's convener Andy Chan Ho-tin publicly advocated "Hong Kong independence" in a talk at the Foreign Correspondents' Club of Hong Kong on Aug 14.

Chan and the FCC were heavily criticized for furthering or aiding the HKNP's separatist agenda.

The HKNP ban received firm support from the central government. The Hong Kong and Macao Affairs Office of the State Council expressed resolute support of the SAR government's decision to put a halt to the operation of the separatist group.

Calling the action "absolutely necessary", the spokesperson of the office said the central government firmly supports punishment for any act that jeopardizes national security in accordance with the law, and has zero tolerance for any organizations preaching "Hong Kong independence" or engaging in activities to split the country.

An unnamed spokesperson for the Liaison Office of the Central People's Government in the HKSAR also voiced support. The HKNP has blatantly advocated and spread the notion of separatism in gross violation of the Constitution, the Basic Law of Hong Kong SAR and relevant local laws, the spokesperson said.

The decision was also hailed in Hong Kong society. In a joint statement, 34 lawmakers in the city fully supported the ban, saying it would serve as a warning for separatists.

Starry Lee Wai-king, chairwoman of the city's largest political party in the legislature－the Democratic Alliance for the Betterment and Progress of Hong Kong－said the government's decision delivers a stern and clear message that advocating "Hong Kong independence" would not be tolerated.

The Hong Kong Federation of Trade Unions said the ban is in line with society's expectations and is reasonable and legitimate.

Starting Monday, Societies Ordinance stipulations on illegal groups took effect on the HKNP. Prohibited actions include running or assisting the operation of the illegal group, acting as a member of the group, providing venues for the group or giving it financial aid. Such acts would incur a fine and a maximum imprisonment of two to three years.

Chan said on Monday that he needed more time before commenting.

The group may appeal the ban within 30 days to the chief executive of the SAR.