The Law of the People's Republic of China on Safeguarding National Security in the Hong Kong Special Administrative Region takes precedence over other local Hong Kong laws, says Basic Law Committee Deputy Director Maria Tam Wai-chu.

She said that's why some arrangements contained in the national security legislation are different from usual judicial practices.

For instance, the chief executive's approval is needed for law enforcers to intercept communications and carry out surveillance, but for other offenses, the court is the approving authority.

The approval of surveillance and interception of communications by the chief executive is quicker and more efficient, Tam said.

"The national security law is parallel with the Basic Law but not part of the Basic Law," she explained. "For this reason, it is stipulated that in case the national security law is in conflict with other Hong Kong laws, the national security law has an overriding effect on other laws of Hong Kong, in the same way as the Basic Law has an overriding effect on other local laws".

According to Article 62 of the law, which was promulgated on Tuesday in Hong Kong, it shall prevail where provisions of the local laws of the HKSAR are inconsistent with the national security law.