China urged the U.S. to stop meddling with Hong Kong affairs on Monday and warned it would take countermeasures if the U.S. implements visa restrictions on officials from the Chinese central government and the Hong Kong Special Administrative Region (HKSAR) government.

Mao Ning, a spokesperson for the Chinese Foreign Ministry, made the remarks after the U.S. announced new visa restrictions on Chinese officials last week as a response to a verdict issued by the Hong Kong court in a case involving conspiring to commit subversion.

Mao said the U.S. had abused visa restrictions, deliberately attacked the principle of "one country, two systems," smeared China's national security law and meddled with HKSAR's judicial matters.

"Such moves blatantly interfere in China's internal affairs, and violate international law and basic norms governing international relations. China strongly deplores and opposes it," she said.

Mao added that the so-called "primary election" organized by those involved in the case who are anti-China and seek to destabilize Hong Kong amounts to a serious challenge to the constitutional order in Hong Kong and endangers national security.

"Among the defendants involved in the case, 31 have already pleaded guilty," the spokesperson said, adding that it is reasonable and lawful for the law enforcement and judicial authorities in HKSAR to carry out their duties in accordance with the law, and punish all acts that undermine national security and that it is firmly supported by the central government.

Mao stressed that Hong Kong affairs are purely China's domestic affairs that brook no external interference.

China urges the U.S. to earnestly respect China's sovereignty and the rule of law in Hong Kong, and abide by international law and basic norms governing international relations, the spokesperson added.

(With input from Xinhua)