(Adds request for Hong Kong govt comment in pararaph 7) HONG KONG, June 30 (Reuters) - Hong Kong authorities have used a new national security law to target dissent and justify "censorship, harassment, arrests and prosecutions that violate human rights", Amnesty International said on Wednesday, a year after the law was implemented. Beijing imposed a sweeping national security law in June last year that sets out punishment for anything it deems as subversion, secession, colluding with foreign forces and terrorism with up to life in prison, setting the city on a more authoritarian path. Authorities have said the law would affect an "extremely small minority" of people and that it had restored stability after months of often-violent protests in 2019. They have said rights and freedoms in the former British colony remain protected but they are not absolute.