An informal poll which kicked off Sunday and gauged support for universal suffrage in Macao was not in line with the Basic Law, according to the city's Chief Executive Fernando Chui Sai-on.

Activists in South China's casino hub of Macao launched a week-long unofficial "referendum" on Sunday, following a similar poll held in Hong Kong in June.

Four staff working for the poll stations were arrested for violations of the privacy law, reported the Macao-based radio and television network Teledifusao de Macau (TDM).

One of the poll's organizers, Jason Chao, said police confiscated their computers during the arrest.

The week-long referendum is expected to last until August 31, when the city will announce the election result for the next chief executive. But the result is a foregone conclusion as the current leader Fernando Chui is the sole candidate seeking another five-year term in office.

Chui said he and his team were informed about the arrest of poll activists on Sunday, and restated that the demands raised in the "referendum" do not fit with the current election methods as stipulated in the Basic Law, reported TDM.

"The 'referendum' organizers do not have the right to collect personal information as such a 'referendum' does not have any legal basis in Macao's judicial system," Macao's Office for Personal Data Protection said.

The office added that it had passed the case to the police after the organizers ignored a warning letter released prior to the poll that urged them to stop collecting voters' personal data. 

Tian Feilong, a law professor and visiting scholar at the University of Hong Kong, said the "referendum" may have been inspired by the similar poll earlier in June in Hong Kong, but said that democracy reform in Macao is at a different stage.

"There has not been a timetable or road map plan for universal suffrage in Macao, so the activists are using the poll as a way to express their discontent," Tian told the Global Times.