HONG KONG (REUTERS) - Hong Kong's security chief said on Friday (Jan 15) that police surveillance of communications can come under the city's national security law, potentially giving officers broader powers of interception.

Mr John Lee, speaking at an online Legislative Council meeting on security, said the Committee of Safeguarding National Security would have oversight over such surveillance operations.

"If it involves crimes endangering national security, they will be dealt with the rules and mechanisms established under the National Security Law," Mr Lee said.

"There are strict regulations on how to deal with the results obtained, when to destroy them, report changes in circumstances... and the police must report to the National Security Commission to supervise the implementation of these rules."

Beijing imposed the national security law on its freest city in June, punishing what it broadly defines as secession, sedition, terrorism and collusion with foreign forces with up to life in jail.

Western governments and human rights groups are concerned that the security law is being used to crush dissent in the Chinese-ruled city.

Authorities in Hong Kong and Beijing say the law is necessary to bring stability to the former British colony after a year of anti-government demonstrations.

While Mr Lee gave few more details of what the surveillance mechanisms would be under the security law, he said such operations would not be subject to rules under the financial hub's existing Interception of Communications and Surveillance Ordinance, under which law enforcement officers must obtain prior approval.

Mr Lee said in cases involving the confidentiality of information within the legal profession and lawyers' clients, those matters would be reported to judges and left for them to decide.

About 100 people have been arrested under the security legislation so far, with some activists saying their phones have been checked or confiscated by authorities.