HONG KONG — More than half a million Hong Kongers have cast ballot, including tens of thousands on Sunday, in the first three days of voting in an unofficial referendum on democratic reform that Beijing has blasted as a farce. Tensions have soared in Hong Kong over how much say residents of the former British colony can have in choosing their next leader, who's currently hand-picked by a 1,200-member committee of mostly pro-Beijing elites. Beijing, which has pledged to allow Hong Kongers to choose their own leader starting in 2017, has balked at letting members of the public nominate their own candidates, saying they would have to be chosen by a Beijing-friendly committee. Pro-democratic organizers of the Occupy Central with Love and Peace movement are offering voters three proposals on so-called public nomination. They've vowed to hold a mass protest if the former British colony's government, which has carried out a consultation on electoral reform, doesn't come up with a proposal that meets their demands. The plan involves rallying at least 10,000 people to shut down the city's central business district and has alarmed businesses in the Asian financial hub. By 4 p.m. Sunday, about 636,000 ballots had been cast since voting started Friday, including about 400,000 through a smartphone app. Nearly 200,000 more were cast online despite a massive cyberattack that left the site intermittently inaccessible and forced organizers to extend voting by a week until June 29. And about 26,500 people cast ballots at 15 polling stations, which organizers were operating on two successive Sundays. The outlook for Hong Kong's democratic development “is quite pessimistic but we are also proactive and we will try our best to make miracles happen,” said Chan Chi-chung, a teacher voting at a Hong Kong Polytechnic University. “If many people come out to voice their opinion, but the Beijing central government ignores that voice, then it's over for Hong Kong.” The central government's liaison office has called the vote “a political farce that overtly challenges the Basic Law,” referring to Hong Kong's mini-constitution that gives the specially administered Chinese city a high degree of autonomy under the principle of “one country, two systems.” Hong Kong's current leader, Chief Executive Leung Chun-ying, has also said the three options don't comply with the law. AP