HONG KONG — Nearly 800,000 people voted in a nonbinding Hong Kong referendum aimed at agitating for greater democracy, organizers said Monday, and the semi-autonomous Chinese city was bracing for hundreds of thousands of people to march through the streets Tuesday to continue pressing their cause.

The 10-day vote in the former British territory – conducted online, via mobile phones and in person – asked residents to cast ballots for one of three mechanisms for directly electing the city’s chief executive.

About 787,000 people – more than 10 percent of the city’s population – participated, organizers said. Mainland authorities have denounced the balloting as illegal.

Under the “One Country, Two Systems” framework governing the city’s return to Chinese rule in 1997, direct voting for the chief executive is to begin in 2017. Rules for the election have not been worked out yet between Hong Kong officials and mainland authorities, but organizers of the referendum fear that the guidelines for the vote will be written so as to allow leaders in Beijing to screen out any potentially objectionable candidates.

Voters also were asked whether the local legislature should veto any proposal that “cannot satisfy international standards allowing genuine choices by electors.” More than 87 percent of voters said yes.