* HK awaits talks between students and city government
* Chief Exec says more time needed to resolve standoff
* Clashes in Mong Kok protest hot spot over weekend (Recasts)
By Donny Kwok and John Ruwitch
HONG KONG, Oct 20 (Reuters) - Hong Kong students and the government stood their ground on Monday ahead of talks aimed at defusing more than three weeks of pro-democracy protests that have blocked traffic around the Chinese-controlled city, but expectations of a breakthrough were low.
Student-led protesters are calling for free elections in the former British trading post, but China insists on screening candidates first. Hong Kong's Beijing-backed leader, Leung Chun-ying, has said the city's government was unwilling to compromise on China's restrictions.
The talks between student representatives and senior city government officials, scheduled for Tuesday evening, may yield small confidence-building measures and an agreement to continue the dialogue, but are unlikely to bridge the chasm between the two sides or end the demonstrations.
"I don't expect much from tomorrow's meeting, but I still hold some hope for the talks," said protester Woody Wong, a 21-year-old student who camped overnight on Nathan Road, the main thoroughfare in the densely populated Mong Kok district.
"I will keep doing this until the government listens."
Dozens of people were injured in two nights of clashes over the weekend in Mong Kok, including 22 police, media and police said. Four people were arrested for assault, police said.
The area was calm on Monday although scores of protesters remained on the streets.
Tuesday's talks, which will be broadcast live, offer a rare opportunity to try to ease the worst political crisis in Hong Kong since Britain handed the free-wheeling city back to China in 1997. The government called off talks scheduled earlier this month after the students called for the protests to expand.
"So far we've seen no hope that they will reach some agreement in the coming week because both sides have different expectations of the dialogue," said James Sung, a political analyst at City University of Hong Kong.
The Hong Kong government's scope for negotiation is severely limited by the ruling Communist Party in Beijing, which at the end of August announced the parameters for the 2017 election of Hong Kong's leader that sparked the protests.
The government may have some wiggle room in determining how the committee that selects candidates for Hong Kong's leadership election is picked, Sung said. The committee is now expected to be stacked with Beijing loyalists, anointing only candidates palatable to China's Communist Party.
"There is some flexibility within the framework, but the problem is whether or not the students will accept it," said Sung. "No one knows because the students are all idealistic."
Leung, who has rejected calls by protesters to quit, said on Sunday that more time was needed to broker what he hoped would be a non-violent end to the upheaval.
"To work out a solution, to put an end to this problem, we need time. We need time to talk to the people, particularly young students," he told Hong Kong's ATV Television. "What I want is to see a peaceful and a meaningful end to this problem."
Hong Kong's 28,000-strong police force has been struggling to contain the movement. Over the weekend, demonstrators in Mong Kok squared off against police in late-night confrontations, surging forward to stake their claim to an intersection.
Scores of riot police smashed batons at a wall of umbrellas that protesters raised to defend themselves. Scuffles erupted amid shouts and hurled insults.
On Sunday night, crowds again built up and protesters stockpiled safety equipment such as helmets. Some wore homemade forearm shields made out of foam pads to parry baton blows.
But unlike the previous two nights, there were no clashes.
Hong Kong is ruled under a "one country, two systems" formula that allows it wide-ranging autonomy and freedoms and specifies universal suffrage as an eventual goal. But Beijing is wary about copycat demands for reform on the mainland.
Leung appears hamstrung, unable to compromise because of the message that would send to people on the mainland, while using more force would likely only galvanize the protests.
Hong Kong Security Chief Lai Tung-kwok said some clashes in recent days had been initiated by activists affiliated to "radical organisations which have been active in conspiring, planning and charging violent acts".
In addition to the four arrested for assault, police on Sunday announced the arrest of a man suspected of inciting others "on an online forum to join the unlawful assembly in Mong Kok, to charge at police and to paralyse the railways".
The arrest of the 23-year-old man for "access to (a) computer with criminal or dishonest intent" appeared to be the first of its kind since the demonstrations began.
Mobile phone chat groups and social media sites like Facebook have been major platforms for protest chatter, including calls for action by demonstration leaders.
Besides Mong Kok, about 1,000 protesters are camped out at the headquarters of the civil disobedience "Occupy" movement on Hong Kong Island in a sea of tents on an eight-lane highway beneath skyscrapers close to government headquarters.
Hong Kong came up in weekend talks between U.S. Secretary of State John Kerry and Chinese State Councillor Yang Jiechi in Boston. A State Department official said it was discussed as part of candid exchanges on human rights. The Chinese Foreign Ministry said Yang told Kerry Hong Kong was an internal affair. (Additional reporting by Elzio Barreto, Yimou Lee, Clare Jim, Irene Jay Liu, Twinnie Siu and Diana Chan and Benjamin Kang Lim in Beijing; Writing by John Ruwitch; Editing by Nick Macfie)