Riot police surrounded Hong Kong's parliament on Monday after authorities said they would go ahead with a proposed extradition law, which would allow suspects to be sent to mainland China, despite protests from an estimated crowd of more than a million. What began as a peaceful protest through the centre of the global financial hub descended into violence early on Monday as several hundred protesters clashed with police, who responded with pepper spray before the stand-off ended soon after. The protests plunged Hong Kong into a new political crisis, heaping pressure on Hong Kong Chief Executive Carrie Lam's administration and her official backers in Beijing. Veteran lawmakers have called on her to resign. The rendition bill has generated unusually broad opposition, from normally pro-establishment business people and lawyers to students, pro-democracy figures and religious groups. Sunday's demonstration capped weeks of growing outrage in the business, diplomatic and legal communities, which fear corrosion of Hong Kong's legal autonomy and the difficulty of ensuring basic judicial protections in mainland China. Ms Lam sought to soothe public concerns and said her administration was creating additional amendments to the bill, including safeguarding human rights. "This bill is not about the mainland alone. This bill is not initiated by the central people's government. I have not received any instruction or mandate from Beijing to do this bill," she said on Monday. She said the bill would have a second reading debate on Wednesday. Organisers put the size of Sunday's crowd at more than a million, outstripping a demonstration in 2003 when 500,000 took to the streets to challenge government plans for tighter national security laws. Police put the figure at 240,000 at the march's peak. Many thousands were still waiting to join the march from Victoria Park on Hong Kong island on Sunday as tens of thousands of others reached the Legislative Council building in the Admiralty business district. About 1,000 people joined a protest in Sydney and another protest was also reported in London. Hong Kong Chief Secretary for Administration Matthew Cheung said on Monday the government had improved the entire proposal to show it had been responding to social demands. "I hope that in the Legislative Council, everyone can continue the discussion in a frank, peaceful and rational way and continue to follow up on this matter," Mr Cheung said. US and European officials have issued formal warnings, matching international business and human rights lobbies that fear the changes would dent Hong Kong's rule of law.