A group of retired American diplomats experienced in navigating the US-China relationship urged Congress on Wednesday to grant Hongkongers seeking political asylum a safe haven in the US.

The letter, signed by nine former US consuls general to Hong Kong – including Kurt Tong and Clifford Hart Jnr, the two most recent US envoys to Hong Kong – and another dozen top former State Department officials, was the latest sign of the furor in Washington over Beijing’s controversial national security law for Hong Kong that went into effect this month.

The law criminalises a wide range of free-speech behaviour under four categories of subversion, secession, terrorism and collusion, and allows Beijing to extradite suspects to the mainland in certain cases. The law is also extraterritorial, covering alleged crimes committed outside the city.

“Beijing’s latest move to impose a new national security law on Hong Kong, even as it circumvented the city’s elected legislature, has undermined the rights of the people of Hong Kong and signalled a fundamental breaking of China’s promises,” the letter said.

“We support efforts in Congress to help the people of Hong Kong who will now be at greater risk of imprisonment and persecution under the new national security law,” it added.

“The situation in Hong Kong is urgent and requires a strong US response rooted firmly in our values and long history of providing safe harbour to those fleeing tyranny.”

Michael Fuchs, a former deputy assistant Secretary of State for East Asian and Pacific Affairs who organised the letter, said that both parties in Congress should want to act in support of Hongkongers wishing to leave the city.

“The absolute minimum that the US should be doing for the people of Hong Kong right now is opening our doors to those who wish to flee an increasingly repressive situation,” he said.

“This should be one issue on which everyone can agree.”

Fear and uncertainty have roiled the city ever since the security law went into effect on July 1. One prominent pro-democracy leader, Nathan Law, already fled Hong Kong and said this week that he had moved to London. The Demosisto Party, the political party that he co-founded, disbanded after Beijing implemented the law.

On Wednesday, The New York Times announced it would be relocating some of its news operation in the city to Seoul, South Korea. In a memo to staff it 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”.

Already this week, the strained US-China relationship has been frayed further amid a wave of Chinese sanctions against US politicians; the Trump administration’s declaration that it would not recognise Chinese control over much of the South China Sea; and State Department warnings of increased “arbitrary detentions” against US citizens in China.

On Tuesday, President Trump signed a new law that would allow the administration to punish Chinese officials who violate Hongkongers’ rights. He also signed an executive order that ends Hong Kong’s preferential trading status, arguing that the security law makes the city no different from any other Chinese city.

The executive order included language that the president would “reallocate admissions within the refugee ceiling” for residents of Hong Kong, “based on humanitarian concerns, to the extent feasible and consistent with applicable law.”

“Their freedom has been taken away,” Trump said on Tuesday of Hongkongers. “Their rights have been taken away and with it goes Hong Kong, in my opinion, because it will no longer be able to compete with free markets.” He added that he thought “a lot of people will be leaving Hong Kong”.

Even so, it’s unclear whether a White House that has made a signature of its resistance to immigrants and asylum seekers would make an exception for people fleeing Hong Kong.

“I can't think of any action the Trump administration has taken to make it easier for any group to enter the United States,” said Sam Wang, a Princeton University professor and head of the Princeton Election Consortium.

“You might want to find out if that is something that Joe Biden would do as president,” he added, referring to Trump’s presumptive Democratic rival in the presidential election in November.

Other countries have already begun making moves to allow Hong Kong refugees.

Britain said it would allow holders of British National (Overseas) passports – a travel status created for people born before the former colony returned to Chinese rule in 1997 – and their dependents to move there with a path to full British citizenship. About 350,000 people have those passports now, and another 2.6 million are eligible to apply for them.

Australia also said it would allow people with Hong Kong passports and currently in the country to stay. Taiwan announced last month that it would offer humanitarian support, including living allowances, to Hongkongers who seek refuge there.

And the EU’s top foreign policy official, Josep Borrell, said this week that the bloc had been “looking at visa possibilities for Hongkongers”.

The issue of granting Hongkongers refugee status has already gained bipartisan support in Congress, despite the bitter debate over immigration and refugees that has been a near-constant theme of the Trump era.

On June 30, as the new security law was poised to take effect, Representative Tom Malinowski, a New Jersey Democrat, and Representative John Curtis, a Republican from Utah, each introduced separate bills to let in new Hong Kong refugees.

Both bills are expected to be combined and introduced as an amendment to the annual Defence Department budget bill. If the House votes to include it, its chances of becoming law would be even higher.

Curtis, whose bill would make Hongkongers seeking asylum in the US “Priority 2 refugees of special humanitarian concern”, called bipartisan support for the issue “strong”.

“The protests in Hong Kong inspired all Americans, Republican and Democrats,” he said.

“This bill and the strong bipartisan coalition in support of this bill shows Hongkongers that we hear them, we value them, we believe in them, and we offer them safe harbour in the US.”