With Hong Kong increasingly polarised on political reforms and fears growing over the influence of Beijing, frustrated residents are pressing former colonial power Britain to offer them an escape route.

Their push for a new status that would allow them right of abode in Britain reflects their anger over what they see as a lack of support from the UK in their time of need.

It follows more than two months of pro-democracy protests, which failed to win concessions from the government on the way the city's next leader is elected, and ties in with concerns that civil liberties are being chipped away.

Before Britain gave the city back to China in 1997 it offered Hong Kongers a special "British National Overseas" (BNO) status to calm those worried about their future under Beijing's rule.

Holders can enter the UK without a visa and get consular assistance abroad, but have no right to live in Britain.

Around 400,000 Hong Kong residents hold the BNO passport and some are now calling on Britain to allow them residency as they seek to escape rising tensions.

"It is an extra option for Hong Kong people -- it's a right they deserve," says Sampson Noble, a 30-year-old Hong Kong Chinese resident who runs the BritishHongKong campaign group.

"I was born British," he added. "It should not relate to my ethnicity."

The group's forum has 3,000 members and has sent letters to British lawmakers, as well as a statement to a UK parliamentary inquiry into Hong Kong's post-handover relationship with Britain.

In that statement the group called Britain's stance "discriminative".

"We were ruled for 156 years and we are being discriminated against," said Humphrey Lau, a campaigner for the group.

"There is a feeling of being betrayed."

Popular Facebook page "BNO Concern", which also calls for right of abode, has 6,000 likes with users dismissing their status as "rubbish" and pushing for change.

Twenty- and thirty-somethings are particularly frustrated, says political columnist Martin Oei.

"Young people are disappointed to see how Hong Kong is greatly affected by the 'Chinese way'," he said.

"People now want to think of a way out."

- Desperate measure -

Before the handover, 50,000 selected Hong Kongers -- mainly white-collar professionals and civil servants -- were given British passports, but more than three million had to make do with BNO status.

Signing up was optional and the status can be held alongside a Chinese passport.

Applying was only possible before the handover, but holders can renew their BNO every 10 years for around HK$1,000 (US$130).

For 33-year-old Peter, a pilot, renewing his BNO passport is a desperate measure.

"(It) is just like someone who is drowning would grasp whatever he can reach," he told AFP, saying the recent democracy protests spurred him to renew the document.

The rallies were sparked by Beijing's insistence that candidates in the city's 2017 leadership vote must be vetted by a loyalist committee, which critics dismiss as "fake democracy".

Attacks on outspoken media figures and the arrests of protest leaders have added to fears that Hong Kong's semi-autonomous status is eroding.

Peter told AFP the failed protests proved "how we are ignored by our government and how helpless we Hong Kong people are".

"The BNO passport may save me one day, when Hong Kong is no longer a place for us and we cannot call ourselves Hong Kong people any more," he added.

- Saving face -

Despite the growing calls, there is no sign that Britain will budge.

"There are currently no plans to amend British Nationality legislation to give holders of BNO status the Right of Abode in the UK, or to extend the right to apply for BNO status," a consulate spokeswoman told AFP.

Critics are sceptical that Britain would ever risk its relationship with China over Hong Kong. UK Foreign Office minister Hugo Swire suggested the strictly-controlled election offered by Beijing could be "better than nothing at all", as he gave evidence to the parliamentary inquiry on Hong Kong last week.

The creation of BNO status was itself widely seen as a bid to keep China happy by not offering Hong Kongers alternative citizenship. It also prevented an influx into Britain.

"The key was to save face on the diplomatic arrangements," says Chung Kim-wah, assistant professor of social science at Hong Kong's Polytechnic University.

"The benefits for Hong Kong were not a primary concern."

Chung said young people's current discontent was "embarrassing" for China.

The older generation are demanding change, too -- Hong Kong residents who served Britain as soldiers have taken their call for right of abode to the UK parliament.

Unless large numbers of BNO-holders can "create noise internationally" there is little chance of change, says Chung.

But for campaigners like Lau, there is no choice but to keep up the pressure.

"If we stop it, we'll get nothing," he said.