Downing Street is reviewing its extradition agreement with Hong Kong as Beijing accused the UK of a “gross interference” in Chinese affairs after the imposition of a restrictive security law.

Amid increasing tensions, No 10 said on Monday that the agreement was being reconsidered with the former British colony in the wake of the controversial legislation.

The announcement came after Chinese ambassador to the UK Liu Xiaoming defended the law that clamps down on liberties as necessary to “prevent, suppress and punish collusion with a foreign country”.

And he accused Westminster of “political manipulation” for offering around three million Hongkongers the right to settle in the UK and ultimately apply for citizenship.

Boris Johnson pledged the move last week after deciding China had committed a “clear and serious breach” of the Sino-British Joint Declaration that aimed to smooth the transition when the territory was handed back to China in 1997.

At a virtual press conference, Mr Liu also accused some British politicians of portraying China as a “threat” or a “hostile country” when discussing Huawei’s role in the 5G network.

“We want to be your friend, we want to be your partner, but if you want to make China a hostile country you have to bear the consequences,” he said.

A short while later, Downing Street urged China not to interfere if British National (Overseas) nationals sought to come to the UK and said Britain is “also reviewing extradition arrangements with Hong Kong”.

“We are currently assessing the national security law and its legal ramifications in terms of extradition with Hong Kong,” the PM’s official spokesman added.

“There are already extensive extradition safeguards in the UK.

“The courts are required to bar a person’s extradition to any country if it would be incompatible with their human rights or if the request appears to be motivated by their political opinion.”

The widely criticised security law Beijing imposed on Hong Kong makes activities deemed subversive or secessionist punishable by imprisonment, and is seen as targeting anti-government demonstrators.

In response to its imposition, the Prime Minister said he would introduce a new route for people in Hong Kong with BNO status to apply for visas to live and work in the UK and ultimately apply for citizenship.

Mr Liu said: “This move constitutes a gross interference in China’s internal affairs.”

We want to be your friend, we want to be your partner, but if you want to make China a hostile country you have to bear the consequences

But he declined to spell out how Beijing will retaliate after the nation said it reserves “the right to take corresponding measures”.

Instead, he said “we have to wait and see” exactly how Britain moves forward.

“Our first response is we criticise the British move, we don’t think they’ve honoured their commitment,” he said.

“Secondly, we think it’s an interference into China’s internal affairs.

“I think this is a political manipulation against this national security law.”

He argued the legislation was needed to safeguard Hong Kong from “external elements” amid sustained pro-independence protests in the city.

“Attempts to disrupt or obstruct the implementation of the national security law for Hong Kong SAR (special administrative region) will be met with the strong opposition of 1.4 billion Chinese people,” Mr Liu said.

“All these attempts are doomed to failure.”