The unofficial "referendum" on Hong Kong's democratic reform will go on despite a threat by a large-scale cyber attack to its voting website, an Occupy Central founder said Tuesday.

The website was overwhelmed by "billions of visits" in 20 hours since online pre-registration commenced on Friday, one of the referendum's organizers Chan Kin-man said in a radio program Tuesday.

He believes such a cyber attack is meant to derail the "referendum" scheduled for June 20 to 22, which is intended to seek popular support for an "occupy" movement to push for universal suffrage in 2017.

The State Council Information Office published a white paper last week, stating that it is a solemn commitment of the central government that ultimately the chief executive will be selected by universal suffrage upon nomination.

Benny Tai, another organizer, assured the poll will continue despite the cyber attack. "We had hoped to get around 200,000 votes, even 300,000," he was quoted as saying by the South China Morning Post.

Emily Lau Wai-hing, a Hong Kong legislator and Chairman of the Democratic Party, told the Global Times Tuesday that she believes such an attack will achieve the opposite result, promoting the poll and attracting more voters. 

The voting time may be extended to accommodate more ballots if the online system does not work as planned, Tai noted.

These attacks are known in computing as distributed denial-of-service attacks, which aim to overwhelm a website with requests.

Xin Haiguang, a Beijing-based Internet expert, told the Global Times that the scale of the attack is rare, but said the intention is not to steal information, but to crash the system. 

A contingency plan is ready and new voting arrangements will be made accordingly, the poll service commissioner of the Public Opinion Program (POP) at the University of Hong Kong told the Global Times.

Besides online voting, Occupy Central also set up 15 voting stations throughout the city to attract local votes on Sunday.

Occupy Central plans to rally protesters to shut down the city's central business district if the government does not provide a plan to implement universal suffrage for the election of the chief executive in 2017.