At a Washington event about the human rights situation in the former British colony, Sebastien Lai said self-censorship in Hong Kong was the anticipated result of the national security crackdown there, but the "hypocrisy" of some governments trying to trade with China was unexpected.

"We are incredibly grateful that the Americans have been a lot stronger on these values that we all share ... than the UK government. The UK government has been incredibly weak,” said Lai, who like his father is a British citizen.

Lai said Britain had not called for the release of his 75-year-old father, who founded the now shut pro-democracy newspaper Apple Daily and faces charges under Hong Kong's security law and a colonial-era sedition law.

"It's very sad to see a democratic government being afraid – or asking permission even – to speak on behalf of one of its citizens that is in prison for freedom of speech," said Lai. "It’s just ridiculous."

Britain's Minister for Investment Dominic Johnson said he held a series of meetings with government officials and executives in Hong Kong this week, the first official visit by a senior British official to the city in five years.

British Prime Minister Rishi Sunak's spokesperson said in January that a junior foreign office minister had met Jimmy Lai's legal team and that the ministry had provided support for him for some time.

U.S. Congressman Mike Gallagher, chair of the House of Representatives select committee on China’s Communist Party, slammed the Vatican for not standing up for Jimmy Lai, who, like him, is a Catholic.

"The silence from the Vatican on China’s human rights abuses and Jimmy’s case, in particular, is deafening," he said.

The Vatican's Washington embassy did not immediately respond to a request for comment.

Gallagher said it was necessary to move human rights back to the center of U.S. foreign policy and to look for "creative ways to put cracks in the Great Firewall” - a reference to China's online censorship.