China issued a fierce rebuke Friday to UN experts who said a draconian national security law imposed upon Hong Kong poses a serious risk to the city's freedoms and breaches international legal obligations.

Beijing has faced a barrage of criticism over the legislation, imposed late June after pro-democracy protests rocked the semi-autonomous city last year.

Media mogul Jimmy Lai was among a group of high-profile pro-democracy figures arrested after the new security law was imposed Media mogul Jimmy Lai was among a group of high-profile pro-democracy figures arrested after the new security law was imposed Photo: AFP / ISAAC LAWRENCE

The law, which criminalises secession, subversion, terrorism and colluding with foreign forces, carries a maximum life sentence and has intimidated many protesters into silence.

In a letter made public Friday, the UN special rapporteurs on human rights warned parts of the legislation "appear to criminalise freedom of expression or any form of criticism" of China.

Key points of China's recently imposed national security law for Hong Kong. Key points of China's recently imposed national security law for Hong Kong. Photo: AFP / John SAEKI

In customarily strong language, China's foreign ministry was swift to strike down the allegations, saying the law "punishes an extremely small number and protects the absolute majority" in the financial hub.

"Some people disregard the facts and maliciously slander China's human rights situation... and crudely interfere in China's internal affairs," ministry spokeswoman Hua Chunying told reporters.

A riot police officer stands guard in a shopping mall in Hong Kong in July after the new national security law was introduced in the city A riot police officer stands guard in a shopping mall in Hong Kong in July after the new national security law was introduced in the city Photo: AFP / ISAAC LAWRENCE

"Stop meddling in Hong Kong affairs and China's affairs in any way."

Hong Kong lurched into chaos last year as pro-democracy protesters -- furious at perceived encroachment by China on the city's freedoms -- clashed with police.

Unrest has simmered down thanks to coronavirus restrictions and the chilling effect of the security law -- under which more than 20 people have been arrested, including a prominent media tycoon.

Critics believe the security law has ended the liberties and autonomy that Beijing promised Hong Kong could keep after its 1997 handover by Britain -- freedoms unique within China Critics believe the security law has ended the liberties and autonomy that Beijing promised Hong Kong could keep after its 1997 handover by Britain -- freedoms unique within China Photo: AFP / May JAMES

The letter by the UN advisers -- the first issued since the law blanketed the southern Chinese city -- gave a vigorous dissection of the damage being inflicted upon the freedoms once enjoyed in Hong Kong, enshrined in an agreement made before the 1997 handover from British colonial rule back to China.

The security law "poses a serious risk that those fundamental freedoms and due process protections may be infringed upon", the rapporteurs said.

The letter warned the legislation could "impinge impermissibly on the rights to freedom of opinion, expression and of peaceful assembly".

The rapporteurs urged China's "reconsideration" of the legislation and for a fully independent reviewer to be appointed to ensure it complies with China's international human rights obligations.

They also expressed concern over one of the most controversial points of the law -- which allows cases to be transferred from the jurisdiction of Hong Kong to mainland China -- and warned it could undermine the right to a fair trial.

The broadly worded law criminalised certain political speech overnight, such as advocating sanctions against China or greater autonomy or independence for Hong Kong.

Lawyers for some of the more than 20 people arrested under the law so far say police are trawling historical actions of pro-democracy activists to beef up their cases.

The UN experts also raised concerns over the definition of terrorism under the national security law.

They warned it extends to damage of physical property such as transport facilities -- which goes well beyond the UN Security Council's definition of terrorist conduct as aiming to cause death or serious bodily harm.