Activists in the Hong Kong Special Administrative Region (SAR) plan to occupy parts of the city's financial district on Tuesday in their appeal for a public nomination process for the city's top post, amid warnings and concerns that the move may spin put of control.

More than a dozen of the city's Legislative Council (LegCo) members belonging to pro-democracy parties Monday urged Hong Kong residents to protest on Tuesday, a day when a pro-democracy and human rights rally has traditionally been staged in Hong Kong every year since 1997. The rally grew in size after 2003.

The LegCo members said that the march, aiming at fighting for "true universal suffrage," should be conducted in a non-violent way and "leave space for Hong Kong government and central authorities" in terms of further negotiation.

Two student organizations, Scholarism and Hong Kong Federation of Students, whose members mostly attend colleges and middle schools, announced Monday that after the rally, they will occupy Chater Road, one of the major roads in the Central district and surround the chief executive's office until 8 am Wednesday.

They anticipate that 2,500 people will take part in the march.

The students' decision came one day after the conclusion of an unofficial "referendum" on electoral reform, in which the poll's organizer claimed nearly 790,000 votes were cast.

The poll let voters pick from three methods, which all include public nomination of the city's chief executive, while a white paper elaborating on the "one country, two systems" released by the central government reiterated last month that candidates for the job should be selected by a nominating committee.

In response to the student organizations' plan, the SAR government said Monday that the government respects residents' freedom and rights to express their opinions and has encouraged them to voice their opinions in a peaceful manner. However, it noted that the police will deal with law-breaking behavior and those who "disrupt the social order" in accordance with the law.

"With students pushing the campaign, the protest is very likely to get out of control," Tam Yiu-chung, chairman of Hong Kong's largest political party, the Democratic Alliance for the Betterment and Progress, told the Global Times.

Tam said normally the annual July 1 protest allows different groups to express their appeals and is part of Hong Kong's political life. "But the students need to be aware of the law," he said.

The movement to seal off the city's financial district was first advocated by the three organizers of the Occupy Central with Love and Peace movement, who planned it to take place at the end of this year.

The trio, who initiated the referendum, said Monday that Tuesday was not the proper time to resort to civil disobedience, but said they respect the students' decision.

"We have a consensus that the movement will be non-violent," said Chan Kin-man, an Occupy Central organizer, adding that he hopes the police will not incite those students who set a time to leave.

The original organizers will gradually lose control of those radical elements, especially students, said Choy Chik-keung, an expert on Hong Kong studies with the Chinese University of Hong Kong.

Concerns were also aroused over whether the referendum will disrupt the commencement of universal suffrage in 2017, as the poll result claimed that 80 percent of voters support LegCo in vetoing the government proposal for election methods if the proposal could not satisfy "international standards."

If the government fails to make a proposal that "satisfies international standards," Tai Yiu-ting, one of the three organizers of Occupy Central, said the government will have to "bear political consequences" brought by their movement.

"If it's not public nomination, they should give an alternative and persuade those 787,767 voters to believe it," he added.

Tam said in that case, the normal procedure of Hong Kong's political reform will be disrupted and it may be not be able to have universal suffrage in 2017.

The Hong Kong and Macao Affairs Office of the State Council Monday released a statement rebuking the referendum.

The statement said the central government respects the rights of Hong Kong citizens to voice their opinion, but any act against the region's Basic Law and the decisions by the top legislature can only obstruct universal suffrage.

Amid recent controversies over the poll, local newspaper Ta Kung Pao voiced concern Monday that Hong Kong may be used as an "anti-China bridgehead and springboard" by Washington, from where a "color revolution" will be spread to the Chinese mainland.

But Zhang Dinghuai, an expert in Hong Kong studies at Shenzhen University, said that the referendum only represents a part of public opinion and that could not be interpreted as Hong Kong becoming a hub of "anti-China" sentiments.

Martin Lee, a pro-democracy activist who organized a protest of lawyers against the central government's white paper on Friday, said even though they have those protests and different opinions over universal suffrage, they still admit and accept the "one country, two systems" policy.