The Hong Kong police and security bureau did not immediately respond to a request for comment.
Hong Kong says 260 people have been arrested under the law, 79 of them convicted for offences including subversion and terrorism.
China and Hong Kong say it was necessary to restore stability in the financial hub.
Yam said he started speaking out about the rule of law in Hong Kong and the crackdown because his friends were in jail.
Reporting by Kirsty Needham in Sydney; Additional reporting by James Pomfret and Jessie Pang in Hong Kong; Editing by William MallardOur Standards: The Thomson Reuters Trust Principles.
Persons:
Kevin Yam, Yam, Mao Ning, Anthony Albanese, Hong, Ted Hui, Richard McGregor, Kirsty Needham, James Pomfret, Jessie Pang, William Mallard
Organizations:
SYDNEY, Hong, HK, Hong Kong, of Australia, Law Society of Hong, Lowy Institute, Thomson
Locations:
Australian, Hong Kong, Hong, Australia, China, Beijing, British, Law Society of Hong Kong, Sydney