Hundreds of Hong Kong police used pepper spray on pro-democracy protesters to clear a major road that had been barricaded with concrete slabs, heightening tensions in the financial hub.
The clashes were the worst in over a week between police and largely student protesters, who late on Tuesday swarmed into a tunnel on a key four-lane thoroughfare, halting traffic and chanting for universal suffrage.
Large numbers of police forced the crowds back, spraying pepper spray at those who resisted. "We're peaceful. We just want democracy. Why are you doing this," one female protester yelled.
Several protesters were wrestled to the ground and taken away. Scores of other officers then entered the tunnel in the Admiralty district and began clearing away makeshift walls formed from concrete slabs, partially reopening the tunnel to traffic.
Protesters have been demanding full democracy for the former British colony, but their two-week campaign has caused traffic chaos and fuelled frustration in the Asian financial centre, draining public support.
China rules Hong Kong under a "one country, two systems" formula that accords the city a degree of autonomy and freedom not enjoyed in mainland China, with universal suffrage an eventual goal.
Beijing said on 31 August that only candidates that get majority backing from a nominating committee stacked with Beijing loyalists would be able to contest a full city-wide vote to choose Hong Kong's next leader in 2017.
Earlier police had used chainsaws and sledge-hammers to clear blockades on another major road in Admiralty.
But hundreds of protesters then stormed into the nearby tunnel, catching authorities by surprise.
The tunnel on Lung Wo Road, an important east-west artery near the offices of the Hong Kong government and legislature had been intentionally left open by demonstrators to traffic.
Despite the reopening of two major thoroughfares to ease what police said was traffic congestion, there was no immediate sign the core protest zone outside government headquarters -where hundreds of tents remain pitched on an eight-lane highway- would be cleared.
Many pro-democracy demonstrators were defiant in the area around the tunnel, guarding the entrance until they were forced back by a cordon of riot and uniformed police, some bearing shields.
