Lee, Hong Kong's number 2 official behind leader Carrie Lam Cheng Yuet-ngor, said the block would not affect his unchallenged campaign bid to lead the former British colony for the next five years in an election scheduled for May 8.

The announcements made by both China's Foreign Ministry and the Hong Kong government came a day after Alphabet Inc, which owns YouTube, said it had taken down Lee's campaign account to comply with US sanction laws.

The US imposed sanctions on Lee and other Hong Kong and Chinese officials in 2020 over what Washington said was their role in curbing the city's freedoms under a national security law Beijing imposed in June that year.

"It is totally wrong and groundless for certain US companies to willingly serve as the US government's political tools to interfere in the internal affairs of other countries citing compliance with sanctions as an excuse," said China's Foreign Ministry spokesman Wang Wenbin.

"The US, out of political purpose, went so far as to undermine freedom of speech ... in order to interfere in Hong Kong affairs."

A spokesman for the Hong Kong government said it "strongly opposed and expressed extreme outrage" at any form of interference in the city's affairs by foreign forces, including the holding of its sixth chief executive election.

"The political structure of the Hong Kong special administrative region is a matter within the purview of the Central Authorities. The international community should fully acknowledge this fact and stop interfering in Hong Kong affairs which are internal affairs of China," it said in a statement on Thursday night.