Beijing is concerned about the possibility of external forces at work in Hong Kong and the city would be "doomed if a 'colour revolution' takes place", a former justice minister warned yesterday. Elsie Leung Oi-sie, now deputy director of the Basic Law Committee under the National People's Congress, defended central government against pan-democrats' criticism that it had reneged on its promise to allow the city a high level of autonomy. Leung spoke out in the wake of controversy surrounding a white paper stressing Beijing's control over Hong Kong under the "one country, two systems" policy. In the paper, Beijing warned that national security would be jeopardised if Hong Kong was not ruled by "patriots". "The central government is worried about the country's situation," Leung said on Commercial Radio. "Hong Kong is such a free city, and many non-residents can [engage in] activities here, so [the white paper] says we have to stay vigilant about whether external forces are meddling in Hong Kong's internal affairs. "Hong Kong would be doomed if we engaged in a 'colour revolution'; in fact, intense movements have been on the rise recently, and I think [Beijing's] worries are not groundless." Colour revolutions, so called because the organisers would use a particular colour to signify their movement, took place in eastern Europe in the early 2000s. Leung did not elaborate on why Hong Kong might go down a similar path, but she is understood to be targeting the Occupy Central campaign, which threatens to mobilise 10,000 people to block traffic in the financial hub as a last push for democracy. She reiterated her worry that the Occupy plan would end in violence - but rejected concerns that military force would be exerted on the civil disobedience action, as happened at Tiananmen Square on June 4, 1989. "Some people are very scared that the [Chinese] army would repeat the political upheaval of June 4 - but it won't. The local garrison would [be mobilised] only if the SAR government asked the central government for help, and then it would be limited to the purpose of maintain public order," Leung said, citing Article 14 of the Basic Law. Occupy organiser Benny Tai Yiu-ting said worries about subversion were similarly unfounded. The movement "has never challenged the country's sovereignty" nor the "one country, two systems" policy, he said. "We have never tried to [engage in] subversion … We are only fighting for genuine universal suffrage," Tai told the RTHK show, City Forum . The debates about the white paper and electoral reform also drew a response from Financial Secretary John Tsang Chun-wah. In his blog, Tsang wrote that the white paper was "released mainly because the central government needed to give a comprehensive statement, as a minority of the people have a vague and one-sided understanding of the Basic Law". "It was not modifying its policy on Hong Kong," he added. Tsang also wrote that he hoped people could fully express their opinions on reform, as that would be "the first step" to achieving consensus. Democratisation would bring a "fundamental change to Hong Kong's governance, and it has great implications" for the city and for China as a whole, he wrote.