The city's pro-Beijing leaders are pushing a bill through the legislature that would allow extraditions to any jurisdiction with which it does not already have a treaty -- including mainland China for the first time

Hong Kong (AFP) - Hong Kong witnessed its largest street protest in at least 15 years on Sunday as crowds massed against plans to allow extraditions to China, a proposal that has sparked a major backlash against the city’s pro-Beijing leadership.

At least 150,000 people marched in blazing summer heat through the cramped streets of the financial hub’s main island in a noisy, colourful demonstration calling on the government to scrap its planned extradition law.

The city’s pro-Beijing leaders are pushing a bill through the legislature that would allow extraditions to any jurisdiction with which it does not already have a treaty – including mainland China for the first time.

Police told AFP at least 153,000 had started the march, but they had yet to calculate the crowd’s peak figure with new people still joining hours after it began.

The proposed law has sparked the biggest public backlash against Hong Kong's pro-Beijing leadership in years

Historically the police give much lower figures than organisers, but even this preliminary estimate would make it the largest street protest since 2003.

Dense crowds chanting “Scrap the evil law!” and “Oppose China extradition!” stretched for miles.

Coffee shop owner Marco Ng said he was closing his store to join the march.

“Our city matters more than our business,” the 26-year-old told AFP. “If we don’t speak out, then there’s no way that the government will listen to our concerns.”

The last time the city saw a protest crowd of similar size was in 2003 when a massive demonstration forced the government to shelve a deeply unpopular national security law.

- Groundswell of opposition -

The extradition plans have sparked an opposition that unites a similarly wide demographic.

In recent weeks lawyers have held sombre marches dressed in black, anonymous senior judges have given critical media interviews and the city’s two main legal groups – the Law Society and the Bar Association – have urged a rethink.

Protesters gathered in Victoria Park before marching to government headquarters

Business figures are also rattled with multiple chambers of commerce and commercial groups expressing alarm, adding to criticism from the United States, Canada, former colonial power Britain and many European governments.

Hong Kong’s leaders, who are not popularly elected, say the law is needed to plug loopholes and stop the city being a bolthole for mainland fugitives.

They say dissidents and critics will not be extradited and have urged the bill’s quick passage to extradite a Hong Kong man who is wanted in Taiwan for murdering his girlfriend.

The proposed law has sparked an opposition that unites a wide demographic, with lawyers and chambers of commerce also expressing alarm

But critics fear the law would entangle people in China’s opaque and politicised court system and say the government is using the Taiwan case as a Trojan Horse.

The proposed law has been fast-tracked through the city’s government-dominated legislature and on Wednesday it will receive its second reading, with plans to have the law on the statute books by late July.

Previous sessions in parliament have descended into chaos with rival lawmakers scuffling.

- Headache for leader -

Sunday’s march was seen by organisers as an attempt to showcase how wide the opposition to the bill is ahead of the second reading.

The backlash creates a headache for the city’s appointed leader Carrie Lam who has staked her political reputation on the bill passing.

Hong Kong's appointed leader Carrie Lam has staked her political reputation on the bill passing

Ignoring such a huge turnout could fuel popular anger or even a return to the unrest of 2014. Organisers told crowds Sunday night that they would “upgrade their actions” if the government ignored the protest.

But backtracking by Lam might embolden opponents and anger Beijing. Several senior Communist Party leaders in China have voiced support for the bill.

In recent weeks Lam’s administration has made some key concessions.

Dense crowds chanting "Scrap the evil law!" and "Oppose China extradition!" stretched for miles

They have removed nine economic crimes from a list of extraditable offences and said only offences that carry seven years or more in jail will be considered, up from three. Requests will only be considered from China’s top prosecuting authority.

Those steps have received a cautious welcome from some business groups, but others have seized on the concessions as a tacit admission that China’s courts are not impartial.

Many protesters on Sunday said they no longer trust the Hong Kong government to stick to promises that critics would never be sent to the mainland.

“This government is not elected… they are only acting for those who gave them power,” Johnny Yuen, a 57-year-old construction worker, said. “Dignity is something we are going to have to fight for ourselves.”

Suspicion of China was worsened by a series of high profile disappearances of people who later appeared in mainland detention, including a group of dissident publishers and a billionaire who disappeared from a top hotel.

Protester Leo Yuen, who said he worked in the arts sector, described the disappearances as “horrifying”.

“You can forsee how easily this would happen again if the bill is passed,” he told AFP.