Video footage appears to show Hong Kong police officers taking a handcuffed pro-democracy protester into a dark corner before repeatedly kicking and beating him.
The man was one of a number of demonstrators knocked down by police armed around an underpass outside the government's headquarters in the early hours of this morning.
ITV News China Correspondent Lucy Watson reports:
Hong Kong police arrested 45 pro-democracy protesters this morning amid violent scenes on a major road in the Asian financial centre.
Video footage shows police using pepper spray on protesters who refused to move and officers wrestling several demonstrators to the ground before taking them away.
Protesters have been demanding full democracy for the former British colony in the wake of restrictions placed by China on the city's next elections in 2017.
Police in Hong Kong have fired pepper spray at Occupy Central protesters as they attempted to clear them out of a tunnel which leads to the city's government headquarters.
Riot officers tore down barricades in and around the underpass hours after a large group of protesters blockaded it.
Activists outnumbered the police officers who were forced to retreat from the area. But they later returned with reinforcements.
Local television reports showed officers taking away dozens of protesters.
Protesters have occupied key parts of the city for more than two weeks to pressure the government into democratic reform.
Hong Kong leader Leung Chun-ying has said there is "almost zero chance" China's government will change its rules for the 2017 election.
A Hong Kong resident says the Occupy Central protests, now in their third week, show another side to a city known for its "cold efficiency".Read the full story ›
Clashes have broken out in Hong Kong after hundreds of people attempted to break down barriers erected by pro-democracy protesters in the city's business district.
The crowd, many wearing masks, chanted "Open the roads" at the protesters who have occupied the area for the past two weeks.
The pro-democracy protesters want Leung Chun-ying to stand down after Beijing ruled out free elections for Hong Kong's leader.
Hong Kong police have begun removing barricades erected by pro-democracy protesters which have been up around the city's financial district for two weeks.
Thousands of students have refused to move, blocking roads in a protest the Hong Kong government has branded "illegal".
But as these pictures show the activists show no sign of backing down as they immediately tried to rebuild the barricades.
The movement, named Occupy Central, have refused to leave until government grants electoral freedom.
A campaign sticker for Scottish independence has found its way onto a wall of the Hong Kong government's headquarters.
The Admiralty district of the city, which hosts many government offices, has been occupied by pro-democracy protesters for more than two weeks.
The area has taken on something of a festival atmosphere with demonstrators camping out in tents and plastering government headquarters in messages written on sticky post-it notes.
Hong Kong leader Leung Chun-ying has vowed to stay in office warning students demanding his resignation that their pro-democracy movement was "out of control".
Leung said the blockade of key parts of the Asian financial hub - now entering its third week - could not continue indefinitely.
In an interview with the local TVB television station, Leung said his government would continue to try to talk with student leaders but did not rule out the use of "minimum force" to clear the area.
Leung added there was "zero chance" that China's leaders in Beijing would change an August decision limiting democracy in Hong Kong.
The former British colony was promised that its freedoms would be protected under a "one country/two systems" formula when Britain handed its old colony back to China 17 years ago.
Pro-democracy activists continue to camp out in Hong Kong two weeks on from when the protests started.
The Occupy Central movement blocked main roads around government headquarters and financial districts.
Earlier in the week the protests were thought to be dying out but hundreds of students have again camped out as it re-gathers momentum after the government called off talks.
Even if talks do go ahead leaders of the protest group have already told supporters to prepare for a long struggle ahead.
ITV News China Correspondent Lucy Watson has posted this image of protesters gathering in Hong Kong earlier this evening after the government called off talks aimed at quelling the unrest.