(CNN) Tens of thousands of Hong Kong residents Sunday protested a proposed law that would that would make it easier to extradite people to mainland China, in what one pro-democracy group has called the city's biggest public demonstration in years.
Demosisto estimated 130,000 protesters marched through the city's streets -- but Hong Kong police put the figure at closer to 22,800.
Either way, the turn out was among the largest since 2014, when Umbrella Movement protesters cut off access to key streets around the city, demanding democratic reforms and free elections.
This weekend's protest was against a proposed law that would allow Hong Kong to extradite fugitives to territories where it doesn't have formal extradition deals, including mainland China, Taiwan and Macau.
The government says the Fugitive Offenders and Mutual Legal Assistance in Criminal Matters Legislation (Amendment) Bill 2019 merely closes loopholes that have prevented officials from bringing criminals to justice.
In a lengthy statement issued Sunday, the government referred to a murder case in Taiwan, where a 20-year-old Hong Kong woman was allegedly killed by her boyfriend while on holiday.
Under its current laws, Hong Kong does not have the legal authority to respond to Taiwan's requests to extradite the suspect. The new bill would change that.
"The Taiwan murder case has clearly shown that serious crimes can happen in any place and at any time ... Hence, we have to plug the loopholes in the current mechanisms as quickly as possible," the government statement said.
It added that "all existing human rights and procedural safeguards provided for in the current legislation will be maintained under the case-based arrangements."
Opponents say the bill could see democracy activists, journalists and foreign business owners surrendered to mainland China.
Hong Kong is a semi-autonomous city, which operates under the principle of "one country, two systems." It has a separate legal system and political system to mainland China and allows citizens to enjoy freedoms not protected on the mainland.
The American Chamber of Commerce, the Hong Kong Journalists Association and the Hong Kong Bar Association have criticized the bill, which still needs to go through a bills committee before it can be passed into law.
The Hong Kong Journalists Association said in a statement that the amendment would "will not only threaten the safety of journalists but also have a chilling effect on the freedom of expression in Hong Kong."
"This sword hanging over journalists will muzzle both the journalists and the whistleblowers, bringing an end to the limited freedom of speech that Hong Kong still enjoys," it said in a statement.
Lam Wing-kee, a bookseller who claims he was kidnapped by Chinese agents in 2015, last Thursday left for Taiwan amid concerns that he could be extradited to mainland China, according to the South China Morning Post.
Lam returned to Hong Kong in 2016 after spending several months in solitary confinement. He was one of five Hong Kong booksellers who disappeared only to later resurface in Chinese custody. All five men were involved with publisher Mighty Current and its shop Causeway Bay Books, which sold gossipy titles about China's elite.
Sunday's protest follows the sentencing of other prominent Occupy leaders, who last week were handed sentences of up to 16 months in prison. Their cases, which were over a range of public nuisance offenses, dragged on for years, draining energy from the pro-democracy protest movement.
Organizers of this weekend's protest have pointed to the relatively high turnout as proof that Hong Kong residents are still concerned about how the city is governed, and are sensitive to any perceived encroachment by Beijing on Hong Kong rights.
Sunday's protest dwarfed an earlier demonstration against the extradition law in March. Organizers estimated that 12,000 took part in the March protest, while police said there were 5,200 at its peak.