The New York Times said Wednesday it was moving its digital news hub from Hong Kong to South Korea as a result of a national security law China imposed on the city last month and trouble obtaining visas.

It is the first major relocation by an international news organisation since authoritarian China enacted its sweeping security law late last month, ramping up control over the semi-autonomous city.

In an email to staff, Times executives said the law "has created a lot of uncertainty about what the new rules will mean to our operation and our journalism".

"We feel it is prudent to make contingency plans and begin to diversify our editing staff around the region."

The newspaper's regional headquarters have been in Hong Kong for decades, overseeing Asia coverage and more recently helping to run the newspaper's 24-hour digital news operation alongside hubs in London and New York.

In its own news report, the Times said it would move the digital team -- roughly one-third of its Hong Kong employees -- to Seoul over the next year.

The Times report also said it had recently faced challenges securing work permits for staff in Hong Kong, something it said was "commonplace in China" but rarely an issue in the former British colony.

In an update, the Times said Chris Buckley, a veteran China specialist at the paper, had been denied a work permit without explanation from Hong Kong's immigration.

Buckley, 52, had to leave China in May after authorities refused to renew his visa there -- a common tactic wielded against foreign reporters on the authoritarian mainland.

China said law-abiding foreign journalists in Hong Kong "do not have any need to worry" under the new law.

"We have an open and welcoming attitude toward foreign media reporting in China," foreign ministry spokeswoman Hua Chunying said at a regular press briefing.

Earlier this year China expelled several journalists working for US news organisations -- including the Times -- in a tit-for-tat spat with Washington.

The newspaper has had a regional headquarters in Hong Kong for decades, overseeing Asia coverage and more recently helping to run the newspaper's 24-hour digital news operation
The newspaper has had a regional headquarters in Hong Kong for decades, overseeing Asia coverage and more recently helping to run the newspaper's 24-hour digital news operation AFP / Anthony WALLACE

Some of the expelled Times journalists have already relocated to Seoul.

The Foreign Correspondents' Club of China said in a March report that 82 percent of journalists surveyed said they had experienced interference, harassment or violence while reporting in China over the past year.

Hong Kong has been a regional nerve centre for international media for decades thanks to its easy business environment and key civil liberties that Beijing pledged to protect until 2047 under the handover deal with Britain.

Alongside the New York Times, media organisations that have major regional hubs in Hong Kong include AFP, CNN, the Wall Street Journal, Bloomberg and the Financial Times.

But Beijing's new security law has sent a chill through the city because its broad wording criminalises some political speech and ramps up Communist Party control.

One provision calls upon authorities to "strengthen the management" of foreign news organisations.

Hong Kong's local government -- which answers to Beijing -- has shown little appetite to defend the media and the city has slid down press freedom rankings in recent years.

Authorities are currently conducting a review of independent but government-funded broadcaster RTHK following criticism it was overly sympathetic to pro-democracy protests that shook the city last year, an allegation the network denies.

Visas for foreign journalists have started to become subject to political pressure.

In 2018, Financial Times journalist Victor Mallet was effectively expelled after he hosted a talk at the Foreign Correspondents' Club of Hong Kong (FCCHK) with a local independence advocate.

The Chinese foreign ministry on Wednesday said Hong Kong's government "has the right to make decisions regarding visa applications in accordance with 'One Country, Two Systems' and the Hong Kong Basic Law," referring to the arrangement created by the handover deal.

At a press conference last week, city leader Carrie Lam was asked by a reporter whether she could "100 percent guarantee" media freedoms.

Lam replied: "If the Foreign Correspondents' Club or reporters in Hong Kong can give me a 100 percent guarantee that they will not commit any offences under this piece of national legislation, then I can do this."