China launched a scathing personal attack on the UN's human rights chief on Thursday, labelling him "unprofessional" after he criticised Beijing's national security law for enabling more restrictions on rights and freedoms.

UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein raised the concerns days after China passed wide-ranging legislation which expands its legal reach over the Internet and even outer space.

The new law "leaves the door wide open to further restrictions of the rights and freedoms of Chinese citizens, and to even tighter control of civil society by the Chinese authorities than there is already," Zeid said Tuesday, according to information released by the UN.

Chinese foreign ministry spokeswoman Hua Chunying said China was "strongly dissatisfied with, and opposed to" Zeid's comments, describing them as "groundless accusations against Chinese normal legislative actions".

"This not only constitutes interference in China's domestic affairs but also reveals he is unprofessional," Hua added.

The comments and their personal nature are unusually direct for China.

Since President Xi Jinping came to power, the ruling Communist Party has enforced stricter controls on the rights of Chinese citizens.

Authorities have cracked down on activists, increased censorship of the media and Internet, and rolled out tough measures to confront what it labels "terrorism" in the far-western region of Xinjiang.

China also released a draft cybersecurity law earlier this week, which sparked concerns from rights groups over increasing censorship of the Internet.

It will allow authorities to shut down the Internet "in some regions" in the event of a security breach, state-run media said Thursday.

It also "stipulates that network operators and Internet authorities are obliged to stop the spread of posts that break laws", the government-published China Daily said.

"They also must record such breaches and report them to appropriate bodies," it added.