The stern message was delivered during a video summit between China and the EU. — AFP/VNA Photo

BEIJING — China rebuffed a warning from the European Union over a new Hong Kong national security law on Tuesday, with the foreign ministry insisting the matter was a "domestic affair".

"We oppose any foreign interference in this matter," said Wang Lutong, director general of European Affairs at China's foreign ministry, adding that China had made its position clear in an EU video summit Monday between President Xi Jinping and top EU officials.

The EU warned China it would face "very negative consequences" if it presses ahead with a new security law for Hong Kong, stepping up pressure on Beijing over the controversial legislation.

European Commission president Ursula von der Leyen and European Council chief Charles Michel told China's top leaders of their "grave concern" over the new law, which critics say will curb the financial hub's autonomy and freedoms.

The stern message, delivered during a video summit on Monday with Chinese President Xi Jinping and Premier Li Keqiang, adds to a chorus of international concern over Hong Kong, though Beijing has shown no sign of backing down on a law it says is necessary to maintain order.

"We expressed our grave concerns about the proposed national security law for Hong Kong," Michel told reporters after the talks.

"We called on China to follow the promises made to the people of Hong Kong and the international community regarding Hong Kong's high degree of autonomy and guaranteed freedoms." — AFP