LONDON/HONG KONG - The number of people from Hong Kong making the decision to leave their hometown and move to Britain since Beijing imposed a strict national security law on the Chinese territory last summer is expected to swell to hundreds of thousands.

Thousands have already made the decision, some because they fear punishment for supporting the pro-democracy protests that swept the former British colony in 2019.

Others say China's encroachment on their way of life and civil liberties has become unbearable, and they want to seek a better future for their children abroad. Most say they do not plan to ever go back.

The moves are expected to accelerate now that five million Hongkongers are eligible to apply for visas to Britain, allowing them to live, work and study there and eventually apply to become British citizens.

Applications for the British National Overseas (BNO) visa officially opened on Sunday, though many have already arrived on British soil to get a head start.

The British government said some 7,000 people with BNO passports — a travel document that Hongkongers could apply for before the city was handed over to Chinese control in 1997 — have arrived since July on the previously allowed six-month visa.

It estimates that over 300,000 people will take up the offer of extended residency rights in the next five years.

Andrew Lo, founder of Anlex Immigration Consultants in Hong Kong, said: "Before the announcement of the BN(O) visa in July, we didn't have many enquiries about UK immigration, maybe less than 10 a month.

"Now we receive about 10 to 15 calls a day asking about it."

Mike, a photojournalist who wanted to be identified only by his first name, said he plans to apply for the visa and move to Leeds with his wife and young daughter in April.

His motivation to leave Hong Kong came after the city's political situation deteriorated following the anti-government protests and he said he realised that the city's police force was not politically neutral.

The police have been criticised by pro-democracy supporters for brutality and the use of excessive violence.

Mike said moving to Britain was important as he believed the education system in Hong Kong would be affected by the political situation and it would be better for his daughter to study in the UK.

Mr Lo said that with the new visa, the barrier to entry to move to the UK becomes extremely low, with no language or education qualification requirements.

BNO passport holders need to prove that they have enough money to support themselves for six months and prove that they are clear of tuberculosis, according to the UK government.

Currently, Mr Lo assists three to four families a week in their move to the UK. About 60% of these are families with young children, while the remaining are young couples or young professionals.

Cindy, a Hong Kong businesswoman and the mother of two young children, arrived in London last week.

In Hong Kong she had a comfortable lifestyle. She owned several properties with her husband and the business she ran was going well. But she made up her mind to leave it all behind as she felt that the city's freedoms and liberties were eroding and she wanted to ensure a good future for her children.

Cindy, who wanted to be identified by her first name only, said it was important to move quickly as she feared Beijing would soon move to halt the exodus.

Prime Minister Boris Johnson said this week that the visa offer showed Britain was honouring its "profound ties of history" with Hong Kong, which was handed over to China on the understanding that it would retain its Western-style freedoms and much of its political autonomy not seen on mainland China.

Beijing said on Friday that it would no longer recognise the BNO passport as a travel document or form of identification, and criticised Britain's citizenship offer as a move that "seriously infringed" on China's sovereignty. It was unclear what effect the announcement would have because many Hongkongers carry multiple passports.

Beijing drastically hardened its stance on Hong Kong after the 2019 protests turned violent and plunged the city into a months-long crisis.

Since the security law's enactment, dozens of pro-democracy activists have been arrested, and the movement's young leaders have either been jailed or fled abroad.

Because the new law broadly defined acts of subversion, secession, foreign collusion and terrorism, many in Hong Kong fear that expressing any form of political opposition — even posting messages on social media — could land them in trouble.

Miriam Lo, who runs Excelsior UK, a relocation agency, said: "This is a really unique emigration wave – some people haven't had time to actually visit the country they're relocating to. Many have no experience of living abroad.

"And because of the pandemic, they couldn't even come over to view a home before deciding to buy."