* Lam says "long road ahead" towards healing city rifts
* Democratic lawmaker Roy Kwong hospitalised after attack
* Amnesty calls for investigation into police actions (Adds AB InBev IPO, National Day guests to be moved indoors)
By Anne Marie Roantree and Donny Kwok
HONG KONG, Sept 24 (Reuters) - Hong Kong leader Carrie Lam said on Tuesday the city's police force, which has been accused of beating activists and using excessive force during protests, is under extreme pressure and acknowledged it will be a "long road" towards healing rifts.
Beijing-backed Lam said it was "quite remarkable" there had not been fatalities during three months of protests, and she hoped dialogue would help resolve the political crisis gripping the Asian financial centre.
Police cast doubt over allegations that officers beat a man during a protest on Saturday, while Amnesty International called on the government to investigate police use of force against demonstrators.
Police Acting Senior Superintendent Vasco Williams told reporters on Monday that footage of the alleged incident appeared to show an "officer kicking a yellow object", not a man, in an alley.
He conceded that the incident needed to be investigated, although he ruled out police "malpractice" and added that the video could have been "doctored".
What started as protests over a now-shelved extradition bill that would have allowed criminal suspects to be sent to mainland China for trial have evolved into broader calls for greater democracy and an independent inquiry into police actions.
Demonstrators are frustrated at what they see as Beijing's tightening grip over the former British colony, which returned to China in 1997 under a "one country, two systems" formula intended to guarantee freedoms not enjoyed on the mainland.
China has said it is committed to the arrangement and denies interfering.
Lam said that, while she supported the police to safeguard the rule of law, "that doesn't mean that I would condone irregularities or wrong practices done by the police force".
"I know the level of mutual trust is now relatively low in Hong Kong, but we have to make sure that we can continue to operate as a civil society," she told reporters.
RED LINES
Lam was speaking after Amnesty called for an investigation into police actions and urged the Hong Kong government to encourage Beijing to safeguard protesters' right to peaceful assembly.
"Ordering an independent and effective investigation into police actions would be a vital first step," Joshua Rosenzweig, head of Amnesty's East Asia regional office, said in a report.
"Authorities need to show they are willing to protect human rights in Hong Kong, even if this means pushing back against Beijing's 'red line'."
In 2017, Chinese President Xi Jinping warned in a speech marking the 20th anniversary of Hong Kong's handover to Beijing that any attempt to undermine China's sovereignty was a "red line" that would not be tolerated.
The protests have weighed on Hong Kong's stock exchange. On Tuesday, the Asia-Pacific unit of brewer Anheuser-Busch InBev NV (AB InBev) raised about $5 billion in a Hong Kong IPO, after being priced at the bottom of a marketed range. In July, the company cancelled plans for an IPO aiming to raise $9.8 billion.
The wider economy has also been hit. The Hong Kong Trade Development Council said on Monday that it expects Hong Kong's exports to shrink by 4% this year, in what would mark its worst export performance in a decade.
LAWMAKER ATTACKED
A democratic lawmaker, Roy Kwong, was taken to hospital on Tuesday after being punched and kicked by three men in the Tin Shui Wai district close to the border with mainland China.
Fellow Democratic Party lawmaker Lam Cheuk-ting said the assailants had suspected triad, or organised criminal backgrounds, and intended "to send a message to threaten all" pro-democracy lawmakers.
Over more than three months, many peaceful protests have degenerated into running battles between black-clad protesters and police, who have responded with tear gas, water cannon, rubber bullets, bean bag rounds and several live rounds fired into the air.
Police, who have also been seen beating protesters on the ground with batons, say they have shown restraint in the face of increased violence, including protesters hurling petrol bombs.
Lam said she hoped a dialogue session on Thursday evening with 150 members of the public would help bridge the divide, but conceded "it will be a long journey to achieve reconciliation in society."
In a direct challenge to Communist Party rulers in mainland China, some protesters have targeted Beijing's representative office in Hong Kong, thrown bricks outside the Chinese People's Liberation Army base and set fire to the Chinese flag.
The city is on edge ahead of the 70th anniversary of the founding of the People's Republic on Oct. 1, with authorities eager to avoid scenes that could embarrass the central government in Beijing.
Lam said all national events should be respected and held in a safe environment.
Guests at a flag-raising ceremony to mark the occasion will be moved indoors so it "can be carried out in a solemn and orderly manner", the Home Affairs Department told Reuters on Tuesday. (Reporting by Anne Marie Roantree, Donny Kwok, James Pomfret, David Kirton, Twinnie Siu and Poppy McPherson in Hong Kong; Editing by Stephen Coates and Alex Richardson)
