China's national security law for Hong Kong poses a serious risk to the city's freedoms and breaches international legal obligations, UN special rapporteurs on human rights have warned. Beijing has faced a groundswell of criticism over the law, which was imposed in late June after pro-democracy protests rocked the semi-autonomous city last year. The law, which criminalises secession, subversion, terrorism and colluding with foreign forces, has intimidated and silenced many protesters.