More than half a million Hongkongers had voted in Occupy Central's unofficial poll on electoral reform by midnight last night, as protest leader Benny Tai Yiu-ting said the controversial plebiscite was "lawful and credible''.
The high turnout came despite a warning on the PopVote website that the "system is under severe attack, only limited service is provided". The voting platform first came under cyberattack when irt was launched on Friday.
By 10am today the number of voters tipped 573,000.
Today the so-called referendum on how Hong Kong should elect its chief executive in 2017 - which opened for online voters at noon on Friday - starts to gather paper ballots at 15 locations across the city.
One polling station will remain open throughout the week, with about 10 more to be added on the final day of voting next Sunday.
Responding to an accusation from the State Council's Hong Kong and Macau Affairs Office that the plebiscite was "unlawful" and not legally binding, Tai said: "I cannot see anything we are doing now is unlawful. If the Chinese authorities say we are doing something unlawful, please point out which acts are unlawful. Are we subject to any criminal liability, and if yes, why not arrest me now?"
"They [the office] have insufficient understanding of the law and rule of law in Hong Kong," Tai said, adding that having no legal basis and being illegal were different concepts and that the poll was protected by civil and political rights guaranteed by the Basic Law.
Legislative Council President Jasper Tsang Yok-sing said the "turnout cannot turn a proposal from being incompatible with the Basic Law to being compatible".
Executive Council convenor Lam Woon-kwong noted that the poll was a way for the public to express their opinion, though he denied it had any legal basis as a referendum. "If there is a clear stance with clear grounds, the government should listen and analyse it regardless of the number of people who expressed that view," he said.
By midnight, 560,089 people had voted online by giving their identity card and mobile phone numbers for verification. Each phone number can be used once only. There are 3.5 million registered voters, but participants in this poll do not need to be on the electoral roll.
The turnout was more than double that in a two-day mock election organised by the University of Hong Kong in 2012, when 223,000 people voted to have their say on who the chief executive should be, while the actual election was decided by a 1,193-strong committee.
Pro-Beijing newspaper Ta Kung Pao yesterday suggested that a possible flaw in the system which might allow vote manipulation was to use a website that can generate valid ID card numbers and then to vote with new mobile phone SIM cards.
Co-organiser of Occupy Central Dr Chan Kin-man acknowledged the system was not perfect, but noted that it would be a costly exercise to arrange for thousands of new SIM cards to make an impact on the poll results. "You can see so many people in the streets or in the train are talking about the vote. We believe the turnout rate is credible," Tai added.
A solution for those who failed to vote online was to go to the polls and cast a paper ballot, which would override the online vote for that ID number, he said.
The poll asks two questions. In the first, voters pick from three proposals for the 2017 chief executive election put forward by civil groups. In the second, voters say if the legislature should veto a future government proposal if it does not satisfy international democratic standards. They can abstain on both questions.
The poll is conducted by the University of Hong Kong's public opinion programme. Occupy Central organisers say they do not interfere in the poll's operation. The poll's website and smartphone app survived what organisers called a "world-class intrusion", a massive distributed denial of service attack of more than 300 gigabits per second at its peak on Friday.
The programme's chief pollster, Dr Robert Chung Ting-yiu, said if there were doubts about the turnout, an independent organisation could be appointed to investigate, adding that he believed the design was reasonable and cautious.
Asked whether the government would listen to the opinion of half a million people, Chief Executive Leung Chun-ying reiterated that the administration "has always valued public opinion", just before he dismissed a key issue in Occupy's poll.
"We hope to achieve universal suffrage in 2017, but the prerequisite is that it has to comply with the Basic Law and the decision of the [national legislature], and the Law Society and Bar Association had said that 'public nomination' doesn't fit into the Basic Law," Leung said.
Each of the proposals - put forward by the Alliance for True Democracy, People Power and a joint one by Scholarism and the Federation of Students - calls for the public to be able to nominate candidates for the 2017 election, a demand Beijing rejects.
A police spokesman said the force would monitor the situation at polling stations today.