There were chaotic scenes, with protesters screaming “Shame!” at police as they tried to shield themselves from the clouds of gas, said AFP reporters in the semi-autonomous Chinese city.

Several scuffles broke out between police in helmets, gas masks and riot gear and demonstrators angered by the tear gas, which was last used in Hong Kong in 2005.

“We are unarmed, just standing here, there was no warning for the gas,” Harry Hung told AFP.

Police fired several more volleys of tear gas on Connaught Road, a main thoroughfare blocked by protesters, before dark.

As night fell thousands dispersed as around 40 police in full riot gear fired canisters of tear gas at the crowd as they walked toward the government headquarters.

“This is unbelievable. This is a peaceful protest and the police are the ones using violence,” said demonstrator Jade Wong. “The level of police violence here is just like mainland China, it was never like this before.”

Police had earlier used hand-held pepper spray on demonstrators who had spilt onto a major multi-lane highway after breaking through barricades set up to stop people joining the crowds camped outside Hong Kong's government headquarters since Friday.

Traffic had ground to a halt on Connaught Road, with police forced to retreat as the protesters rushed toward the crowds outside government headquarters on the other side. They cheered and embraced each other in the middle of the road, a major city artery usually filled with whizzing taxis and buses.

China, which stations a military garrison in Hong Kong, said it was confident the city's administration could handle the protest.

Beijing “firmly opposes all illegal activities that could undermine rule of law and jeopardize 'social tranquility' and it offers its strong backing” to the Hong Kong government, a spokesman for China's Hong Kong and Macau affairs office was quoted by Xinhua News Agency as saying.

The extraordinary scenes came at the climax of a week of student-led action against China's refusal to grant full democracy to the former British colony.

Students have boycotted classes in the past week, while the increasingly tense protests have also seen them mob the city's leader and storm into the complex housing government headquarters.Beijing said that while it would allow elections for Hong Kong's leader in 2017, it would insist on vetting the candidates.

Prominent pro-democracy group Occupy Central threw its weight behind the protests on Sunday, saying they were bringing forward a mass civil disobedience campaign that had been due to start on Oct. 1.

“Occupy Central starts now,” Tai told the crowds outside government headquarters.

The group had sparked months of heated debate in the city of seven million over its plan to bring Hong Kong's financial district to a standstill with a mass sit-in. On Sunday they appeared to have come close to reaching that goal.

Hong Kong's leader, Chief Executive Leung Chun-ying, told a press conference his administration was “resolute in opposing the unlawful occupation actions by Occupy Central.”

He said his government would hold more public consultations on the planned political changes — a move already scheduled before the protests.

Ryan Chung, a 19-year-old student watching events unfold, said: “We have the right to stay here and to protest. The world needs to know what is happening in Hong Kong. They need to know we want democracy but don't have it.”

The crowds of protesters camped outside the city's government headquarters had swelled on Saturday night to more than 10,000, with scuffles with police overnight as lines of officers pushed back surges of people with riot shields.

催淚彈射向亂港抗議

亞倫潭，法新社
2014年9月29日，上午12:01過

香港 - 警方一再發射催淚瓦斯的親民主示威者數以萬計後帶來香港的中心部分癱瘓週日的抗議活動的急劇升級已經籠罩著城市的日子。

有混亂的場面，有示威者大喊“不要臉！”在警察，因為他們試圖從氣體雲中保護自己，法新社說，記者在半自治的中國城市。

一些混戰爆發了警察頭盔，防毒面具和防暴裝備和示威者的催淚瓦斯激怒了，上一次是在2005年在香港使用的是間。

“我們是手無寸鐵，只是站在這裡，並沒有警告的氣，”哈利紅告訴法新社。

警方發射催淚瓦斯的幾個齊射幹諾道，阻止示威者的一條主幹道，天黑前。

夜幕降臨成千上萬分散的各地40名警察全部防暴發射催淚氣體罐的人群，因為他們對政府的總部走去。

“這是令人難以置信的。這是一個和平的抗議和警察使用暴力的人，“驗證機皇玉說。“這裡的警察暴力的程度就像中國大陸，這是從來沒有喜歡這之前。”

警方對誰通過設置路障破阻止人們參與的人群駐紮香港政府總部門外，因為週五曾濺上一大的多車道公路示威者先前使用手持胡椒噴霧。

交通已經幹諾道停了下來，警察被迫撤退的抗議者政府總部外的另一邊沖向人群。他們歡呼雀躍，並在路上，一個主要城市動脈通常充斥著呼嘯而過出租車和公交車的中間相互輝映。

中國，這台在香港的軍事要塞，說這是自信的城市管理可以處理的抗議。

北京“堅決反對任何可能破壞法治，破壞”社會安定“的所有非法活動，它提供了強大的後盾”，以香港政府的一位發言人對中國香港和澳門事務辦公室是由新華社引述說。

非凡的場景是在一個星期對中國拒絕學生領導的行動的高潮給予充分民主的前英國殖民地。

學生們在過去一周罷課，而日益緊張的抗議活動也看到了他們的暴徒城市的領導者和風暴到複雜的住房政府總部。北京說，雖然這將使選舉對香港的領導人在2017年，它將堅持審查候選人。

著名民運團體佔領中環投擲重量的抗議活動背後的週日，他說，他們提前了曾經由於啟動10月1日大規模公民抗命運動。

“佔領中環現在開始，”泰對政府總部外的人群。

該集團曾引發了全市700萬激辯個月以上的計劃，使香港的金融區陷入癱瘓與群眾靜坐。上週日，他們似乎已接近實現這一目標。

香港的領袖，行政長官梁振英，在記者會上說，他的政府是“堅決按中央佔據反對非法佔領行動。”

他說，他的政府將堅持計劃的政治變化更多的公眾諮詢 - 已經安排的抗議活動之前的舉動。

瑞安湧，一名19歲的學生看著事態的發展，說：“我們要留在這裡和抗議的權利。世界需要知道什麼是發生在香港。他們需要知道我們要民主，但沒有它。“

抗議者城市的政府總部門外紮營的人群鼓起了上週六晚1萬多，與混戰與警方通宵警務人員的行推後潮人用防暴盾牌。