The front, a coalition of human rights and pro-democracy groups, said 130,000 took part in the march from Causeway Bay to the Legislative Council in Admiralty, while police estimated that at its height, 22,800 joined.

Marchers took more than four hours to make their way along the 2.2km route.

Chief Secretary Matthew Cheung Kin-chung, the city’s No 2 official, said Hong Kong people enjoyed the freedom of speech and of assembly and the right to stage protests.

“But it has to be conducted in a lawful manner. Whether the turnout is big or small is not the main concern,” he said.

Fugitive law coming even if murder suspect has walked free, Lee says

Cheung dismissed worries about possible abuse of the proposed extradition arrangement, saying it would not apply to cases involving human rights, politics or capital punishment.

The government promised it would consider each case carefully, saying the executive authority and the court would perform their respective gatekeeping roles in handling all surrender requests. It said it would reject any surrender request that did not meet legal requirements.

Executive Council member Ronny Tong Ka-wah had earlier urged the government not to bow to pressure, no matter the size of the protest.

“The opposition voices are all political slogans. The worries expressed are due to misunderstandings of the proposed changes … Public views that are not convincing are not representative,” said Tong, a barrister. “It is the best time [to change the law] … If the government surrenders just because there are some opposing voices, I am afraid it will be difficult to have effective governance in the future.”

The front organised a similar march last month and claimed a turnout of 12,000, but police estimated 5,200 took part.

Speaking after Sunday’s rally, front vice convenor Figo Chan Ho-hang threatened to escalate its opposition in May if the government did not retract the amendment.

“If the government does not respond to the public’s demands … the front will take action to surround Legco,” Chan said, without offering details.

He said the higher attendance this time was related to the jailing of four Occupy movement leaders on Wednesday.

The turnout was the largest since an estimated 510,000 joined the annual July 1 protest in 2014.

Outspoken businessman Lew Mon-hung was among Sunday’s marchers, holding a placard that read: “Protect ‘one country, two systems’,” a reference to the policy under which Beijing governs Hong Kong.

“I hope members of the business sector can learn the public’s view, and not move against the current of the times,” he said.

Polly Lau, a retired civil servant, said the amendment put Hongkongers at risk of being sent to the mainland to stand trial. “I think the government is acting like the enemy of the people.”

Steven Mak Wai-ming, a clerk who marched with his wife and nine-year-old daughter, said he did not trust the mainland’s legal system. “I have a child, what will the future be like? So, I had to come out,” he said.

Some protesters held photos of the four jailed Occupy leaders – co-founders Benny Tai Yiu-ting and Dr Chan Kin-man, lawmaker Shiu Ka-chun and League of Social Democrats vice-chairman Raphael Wong Ho-ming.

Amid pressure from the business community, the government watered down its extradition proposal by removing nine economic crimes related to tax, securities and futures, as well as the unlawful use of a computer, from the list of extraditable offences. But the sector’s opposition remains.

If the amendment is passed, Hong Kong will be able to hand over fugitives to jurisdictions with which it has no extradition deal, including the mainland, Taiwan, and Macau.

The city’s leader will be empowered to issue a certificate requesting the arrest of a fugitive upon an extradition request, with a court deciding on the outcome.

Bookseller leaves for Taiwan, fearing proposed extradition law

Critics fear Beijing could abuse the new arrangement to target political activists. Human rights groups also claim forced confessions and arbitrary detention are routine on the mainland.

Man wanted in Taiwan murder case ‘could escape extradition’

The march also fell on the eve of the sentencing of Hongkonger Chan Tong-kai, the man at the centre of the firestorm over the extradition law. Chan was earlier arrested locally over the theft of his girlfriend’s bank card, camera, phone and cash. He pleaded guilty to money laundering charges. He is wanted in Taiwan, accused by police there of murdering his girlfriend when they visited the island last year.

Chan managed to return to Hong Kong and cannot be sent to Taiwan to stand trial because there is no legal framework between the two sides allowing his extradition.

In pushing for the changes, the government said its amendment bill was aimed at closing such a loophole so fugitives could be brought to justice. Officials expect to pass it by the end of the current legislative term in July.

Barrister Stephen Char Shik-ngor, a former ICAC chief investigator, said it was a mistake for the government to seek to resolve the Taiwan case via the amendment.

“If it was so concerned with doing justice, it could have done it a year ago,” Char said.

He also said the government could have extended the city’s jurisdiction to Taiwan and sought to try the murder locally, by way of another amendment to the law.