* Organisers say more than 1 million take to streets

* Riot police surround parliament after early morning clashes with holdout protesters

* Pressure building on Hong Kong leader (.)

By James Pomfret and Anne Marie Roantree

HONG KONG, June 9 (Reuters) - Riot police surrounded Hong Kong's parliament early on Monday after what had been a peaceful million-strong protest against an extradition bill descended into running clashes between police and protesters.

Several hundred riot police armed with batons, shields, tear gas guns and pepper spray sealed off the Legislative Council as a similar number of protesters charged their lines shortly after midnight, Reuters witnesses said.

Police used batons and fired pepper spray at protesters, who still managed to close off part of a nearby road. Several people on both sides appeared to be injured, and ambulances were called. Metal barriers were left twisted and torn in the clashes.

The Legislative Council is where debates will start on Wednesday to pass a new government bill that will allow suspects wanted in mainland China to be sent across the border for trial.

Earlier on Sunday, hundreds of thousands had jammed Hong Kong's streets to protest the bill in the biggest demonstration in years. Many said they feared it put the city's vaunted legal independence at risk.

The rallies -- and the violence -- plunge the global financial hub into a fresh political crisis, with marchers and opposition leaders demanding the bill be shelved and that the city's Beijing-backed Chief Executive Carrie Lam resign.

After seven hours of marching, organisers estimated 1,030,000 people took part, far outstripping a demonstration in 2003 when half that number hit the streets to successfully challenge government plans for tighter national security laws.

A police spokesman said police estimated 240,000 were on the march "at its peak".

"She (Lam) has to withdraw the bill and resign," veteran Democratic Party lawmaker James To told crowds gathering outside the council and government headquarters in the Admiralty business district on Sunday night.

"The whole of Hong Kong is against her."

As To spoke, thousands were still arriving at the march that started five hours earlier and filled four lanes of a major thoroughfare.

Some sat in a nearby park singing gospel standard "Hallelujah" even as ranks of riot police started to congregate.

Lam had yet to comment on the rally and the future of the bill, which could be passed into law by the end of June. She has tweaked the amendments but refused to pull the bill, saying it is vital to plug a long-standing "loophole".

The demonstration capped weeks of growing outrage in the business, diplomatic and legal communities, and human rights groups, which fear corrosion of Hong Kong's rule of law and the the lack of an fair and open legal system on the mainland.

The former British colony was handed back to China in 1997 amid guarantees of autonomy and various freedoms including a separate legal system, which many diplomats and business leaders believe is its strongest remaining asset.

The unusually broad opposition to the rendition bill displayed on Sunday came amid a series of government moves to deepen links between southern mainland China and Hong Kong.

Chants of "no China extradition, no evil law" echoed through the streets of the high-rise city as marchers snaked through the Causeway Bay and Wanchai shopping districts.

Some carried yellow umbrellas, a symbol of the 2014 pro-democracy Occupy protests that choked city streets for 79 days.

BROAD-BASED, GOOD-NATURED PROTEST

One protester held a sign reading "Carry off Carrie", while another declared "Extradite yourself, Carrie".

The genial crowd included families with prams and elderly people who sprayed each other with water misters in the 32 degree C (90°F) heat.

Opposition to the bill has united a broad range of the community, from usually pro-establishment business people and lawyers to students, pro-democracy figures and religious groups.

Insurance agents, executives and small entrepreneurs joined bus drivers and mechanics in the streets on Sunday. Dozens of people told Reuters it was their first protest march, with some remarking on the strong sense of unity among the diverse crowds.

Schoolteacher Garry Chiu joined the protest with his wife and one-year-old daughter, saying: "It is no longer about me."

"I need to save my daughter. If the law is implemented anyone can disappear from Hong Kong. No one will get justice in China. We know there are no human rights," Chiu added.

Protests against the bill were held on Sunday in 26 cities globally, including London, Sydney, New York and Chicago.

"The extradition bill will directly threaten the core values of Hong Kong and rule of law," said 21-year-old Kelvin Tam, a student in London. "It will remove the firewall of Hong Kong judicial independence."

CRITICISM OF BILL

The amendments would simplify case-by-case arrangements to allow extradition of wanted suspects to jurisdictions, including mainland China, Macau and Taiwan, beyond the 20 with which Hong Kong already has extradition treaties.

Foreign governments have also expressed concern, warning of the impact on Hong Kong's reputation as an international financial hub, and noting that foreigners wanted in China risk getting ensnared in Hong Kong.

Concerns were highlighted on Saturday with news that a local high court judge had been reprimanded by the chief justice after his signature appeared on a public petition against the bill.

Human rights groups have repeatedly cited the alleged use of torture, arbitrary detentions, forced confessions and problems accessing lawyers in China.

Hong Kong officials have defended the plans, even as they raised the threshold of extraditable offences to crimes carrying penalties of seven years or more.

They cite safeguards including the protection of independent local judges who will hear cases before any approval by the Hong Kong chief executive. No one would be extradited if they face political or religious persecution or torture, or the death penalty, they say.

"We continue to listen to a wide cross-section of views and opinions and remain to open to suggestions on ways to improve the new regime," a government official said on Sunday.

(For the most recent stories on the extradition debate, click on. For a story explaining the issues, see ) (Additional reporting by Clare Jim, Farah Master, Anne Marie Roantree, Jessie Pang, Shellin Li, Forina Fu, Vimvam Tong, Aleksander Solum and Twinnie Siu Writing by Greg Torode Editing by Catherine Evans)

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