(AFP) - After weeks of increasingly violent protests, China's top policy body on Hong Kong affairs was set to hold an extremely rare press briefing Monday on the crisis engulfing the financial hub, where dozens of protesters were arrested in weekend clashes with police.

What began as a mass display of opposition to an extradition bill two months ago has morphed into a wider pro-democracy movement that has thrown down the most significant challenge to Beijing's authority since the former British colony returned to Chinese rule in 1997.

While China has issued increasingly shrill condemnations of the protests in the last two weeks, it has largely left the city's pro-Beijing administration to deal with the situation.

So Monday’s highly unusual press briefing in Beijing by the cabinet-level Hong Kong and Macau Affairs Office will be closely watched for any hint of more direct intervention.

In an editorial on Monday, the state-run China Daily newspaper signalled the growing concern in Beijing.

"What is happening in Hong Kong is no longer the airing of real or imagined grievances," the editorial said.

"It is of the same hue as the colour revolutions that were instigated in the Middle East and North Africa - local anti-government elements colluding with external forces to topple governments utilising modern communication technology to spread rumours, distrust and fear."

- Another weekend of violence -

Pro-democracy protesters fought a second consecutive day of running battles with police on Sunday evening in a well-heeled residential district of Hong Kong, in some of the most sustained scenes of violence witnessed so far.

The clashes took place close to the Liaison Office, which represents Beijing in the semi-autonomous territory.

In a statement early Monday, police said 49 "radical protesters" had been arrested for a variety of offences on Sunday saying the crowds were getting "increasingly violent".

Police said protesters hurled bricks, bottles, paint bombs, corrosive liquids and used a crossbow to fire metal ball bearings. Bows and arrows were also later recovered from the scene, the force said.

Sustained volleys of tear gas and rubber bullets arced through the air to clear the streets with elite units known as "Raptor" squads arresting those left behind, almost all of them young men and women.

Medical authorities early Monday said 16 people were injured.

Sunday's violence came a day after police fired tear gas and rubber bullets at protesters holding a banned rally against suspected pro-government triad gangs in a town near the border with mainland China.

The gangs had beaten up democracy demonstrators there the previous weekend.

Police made 13 arrests that day while hospital authorities said a total of 24 people were hurt, two seriously.

- Unprecedented anger -

Despite facing unprecedented levels of public anger and frustration that has seen millions take to the streets, the city's pro-Beijing leadership have appeared unable, or unwilling, to end the chaos.

The demonstrations were triggered by a bill -- now suspended -- that would have allowed extraditions to mainland China, but have evolved into a call for wider democratic reforms and a halt to eroding freedoms.

In a direct challenge to Beijing, the protestors have seized opportunities to target and deface symbols of China's sovereignty over Hong Kong.

Pro-democracy lawmaker Claudia Mo said the city was now trapped in a "vicious cycle" where huge peaceful marches that have been ignored by the government end with violence between police and small groups of hardcore protesters.

"You see force being escalated on both sides. But then this is a huge imbalance because the police are in possession of deadly weapons. This sums up Hong Kong today," she told AFP.

- Battle for Yuen Long -

Public anger reached new levels a week ago when a pro-government mob of men wearing white shirts and armed with sticks attacked protesters in Yuen Long, in Hong Kong's rural New Territories where many of the surrounding villages are known for triad gang connections and their staunch support for the pro-Beijing establishment.

That brazen assault left at least 45 people taken to hospital, and police were heavily criticised for being too slow to respond with some pro-democracy activists accusing the force of colluding with the triads.

In a rare move, police banned Saturday's counter-rally, saying they feared reprisal attacks against villagers from protesters.

They also banned a proposed march on Sunday. But on both days protesters simply ignored the orders.

© Agence France-Presse