The websites of the city's biggest political party, the Occupy Central movement and the Silent Majority for Hong Kong were all taken offline by hackers yesterday after a US-based group declared cyberwar on the Hong Kong government. At 7.45pm, the website of the Beijing-loyalist Democratic Alliance for the Betterment and Progress of Hong Kong remained down, and access to the Occupy Central and Silent Majority sites was intermittent. The hackers' group, known as Anonymous, posted on its various Twitter accounts and its Asia arm's Facebook page that hackers had started a distributed denial-of-service (DDoS) attack against the sites yesterday morning. The cyberattacks bombarded the sites with traffic, overloading their servers and forcing them offline by the afternoon. DAB chairman Tam Yiu-chung described the cyberattack as "outrageous", adding that staff were working to get the party's site back online. Anonymous declared cyberwar on Hong Kong on Thursday after police used tear gas on unarmed demonstrators during the Occupy protests on September 28. In a video sent to US news portal News2share, the group said: "We are watching you very closely and have already begun to wage war on you for your inhumane actions against your own citizens." The group said it would deface and take offline all of the government's web-based assets if the government and police continued to "abuse, harass or harm" protesters. "That is not a threat. It is a promise," a member said in the video. He also threatened to disclose all government officials' personal information online: "We will seize all your databases and email pools and dump them on the internet. This is your first and only warning." Addressing Hong Kong protesters, the member said: "We have heard your plea for help. Take heart and take to your streets. You are not alone in this fight. Anonymous members all over the world stand with you and will help in your fight for democracy." In response, a police spokesman said: "The cyberworld of the internet is not a virtual space not bound by law." The Office of the Government Chief Information Officer said: "Government information systems are now under normal operation. No abnormality was identified." Anyone convicted of accessing a computer with dishonest or criminal intent under Section 161 of Chapter 200 of the Crime Ordinance faces up to five years in jail. Anonymous - founded in 2003 - is best known for its cyberattacks on the FBI, the Visa credit-card network and electronics giant Sony. It has about 20 members in Hong Kong. Two years ago, one of its Hong Kong members was arrested for posting comments online saying that he would hack several government websites.