Pro-democracy legislators in Hong Kong walked out of the chamber Wednesday to protest the government's intention to stick with a proposal to screen candidates for the city's top executive in 2017, an issue that sparked massive street protests throughout the fall.

Chief Secretary Carrie Lam, the city's No. 2 official, opened a second consultation on the electoral process by addressing the territory's Legislative Council. Lawmakers aligned with the pro-democracy movement calling for free elections immediately protested by raising yellow umbrellas — symbols of the protests— and walked out.

Pro-democracy legislators hold 40 per cent of seats, enough to block the election plan.

They accuse leaders in Hong Kong and mainland China of breaking promises to let the city choose its chief executive through universal suffrage. The central Chinese government had pledged such a vote when the financial hub of seven million people was handed from colonial British to Chinese rule in 1997, under a form of autonomy dubbed "one country, two systems."

"I urge the members to think twice and not completely destroy the limited space for political discussion even before the second consultation has started," Lam said to a half-empty chamber. "Many of my friends feel extreme pessimism whether this proposal of universal suffrage can be passed. ... We will make our best endeavours until the last moment."

The Hong Kong government said in a report Tuesday that it remained committed to a Beijing-crafted plan requiring that candidates be picked by a committee believed to be biased toward the mainland Chinese government. That plan was reached in August and prompted thousands of protesters to block streets in Hong Kong for more than two months demanding open nominations for chief executive.

The report noted that "constitutional development is an extremely controversial issue," but said it was the "common aspiration" of Hong Kong's residents, its government and Beijing authorities to implement the vote according to the city's own Basic Law and the decision by the Chinese National People's Congress Standing Committee.

The council must approve any election plan by a two-thirds majority, and then submit it to authorities in Beijing.

Pro-democracy legislators had debated whether to vote down a plan that includes the proposed nominating committee, a move that would keep in place the territory's current system of choosing its chief executive directly through an election committee that many believe also favours Beijing.