Hong Kong activists launched their fightback Monday against Beijing's landmark decision to limit voting reforms, heckling a senior Chinese official in angry scenes after hopes for full democracy were crushed.

Li Fei, a member of the top committee of China's rubber stamp parliament, was forced to speak over the cries of pro-democracy lawmakers and protesters during a meeting with local officials in the southern Chinese city.

Brief scuffles erupted outside the venue as police deployed pepper spray to stop protesters from storming the hall where Li told delegates that China will not tolerate a local leader who is disloyal to the mainland.

"Anyone who does not love the country, love Hong Kong or is confrontational towards the central government shall not be the chief executive," he said.

His visit comes a day after democracy activists vowed an "era of civil disobedience" including mass sit-ins of the international trading hub's financial district in response to Beijing's decision to grant only limited suffrage to the former British colony.

For years activists have agitated for the right to both nominate and vote for Hong Kong's leader, a campaign buoyed by a recent surge in discontent over rising inequality and perceived interference by Beijing.

But their hopes were dashed Sunday when the standing committee of the National People's Congress announced citizens will only be able to vote for candidates who have obtained the backing of more than half the members of a pro-Beijing committee.

Democracy activists have called the restrictive framework a betrayal of Beijing's promise to award Hong Kong universal suffrage by 2017 and say the nominating committee would ensure a sympathetic slate of candidates and exclude dissidents.

'Broken promises'

As Li approached the lectern to speak at the Asia World Expo convention centre, veteran dissident lawmaker Leung Kwok-hung started shouting him down, his fist raised in the air.

He was joined by a dozen pro-democracy lawmakers and some younger demonstrators who unfurled a banner in front of the lectern where Li was speaking from and chanted: "The central government broke its promise, shameless."

The meeting was briefly suspended while security officers removed the hecklers, to loud cheers and applause from pro-Beijing lawmakers.

"The protesters behaved violently and they charged towards the security guards and police officers," police officer Kwok Pak-chung told reporters.

"Our officers gave warnings repeatedly... two of them finally discharged (pepper spray) three times before protesters ceased their action."

Delivering his speech in Mandarin in the largely Cantonese speaking city, Li warned pro-democracy activists against seeking a break from Beijing.

"(Those who) wish Hong Kong will become an independent political entity or will change the country's socialist system will not have a political future," he said.

Beijing's proposal still needs to win two-thirds support in the city's 70-seat legislature where at least 25 pro-democracy lawmakers have vowed to vote against it.

If it fails however, China has insisted that the next chief executive will simply be chosen by the same pro-Beijing committee that selected the city's current leader Leung Chun-ying.

Dogged by protests

Li flew into Hong Kong from Beijing late Sunday and was forced to drive past a crowd of largely student protesters who had gathered outside his hotel, in the kind of scenes that would be unthinkable on the Chinese mainland.

Britain handed Hong Kong back to China on July 1, 1997 under a "one country, two systems" agreement which allows residents civil liberties not seen on the mainland, including free speech and the right to protest.

Following Beijing's decision to vet candidates, the pro-democracy group Occupy Central said Sunday it would go ahead with its threat to take over the city's Central financial district in protest, at an unspecified date.

Shortly before Li's speech, activists launched what they described as a "slow drive" through the city, the first of a string of small-scale civil disobedience acts that have been promised.

Some 10 cars, decked with flags, made their way deliberately slowly through the city accompanied by police motorcycles, but traffic was not noticeably disrupted.

Chinese state media Monday said those embarking on a civil disobedience campaign were destined to fail.

"The radical opposition camp is doomed to be a paper tiger in front of Hong Kong's mainstream public opinion and the firm resolution of the central government," wrote the Global Times, which is close to the ruling Communist Party, in an editorial.

The government-published China Daily added: "The people of Hong Kong have a critical decision to make: to embrace a hitherto unprecedented level of democracy, or the disruptive, reckless political gamble to be staged by the radicals."