BEIJING (AFP) - Beijing on Thursday defended Hong Kong's plan to vet candidates for its 2017 leadership election, saying it represented public opinion "from all walks of life" in the territory despite mass pro-democracy protests on the issue last year.

The statement by China's foreign ministry came as Hong Kong's leader Leung Chun Ying hit back at "uncivilised" critics after he was booed and heckled by local residents.

New York-based Human Rights Watch denounced the election plan as a "farce", a "rejection of international law" and a "betrayal of democratic aspirations in Hong Kong".

But Chinese foreign ministry spokesman Hong Lei countered: "We certainly cannot agree with such accusations".

The roadmap "represents the public opinions from all walks of life in Hong Kong towards the referendum of the chief executive of Hong Kong", Hong told a regular briefing of reporters.

He added that the plan "meets the realities of Hong Kong, accommodates the rights and interests of Hong Kong people and is a viable, reasonable and pragmatic solution".

The roadmap for the city's first ever public vote for its chief executive was announced on Wednesday. It conforms to a controversial Chinese decision that candidates in the poll must first be approved by a pro-Beijing committee.

That ruling sparked more than two months of mass protests last year.

Britain handed Hong Kong over to China in 1997 under a joint declaration which guaranteed political, social and economic freedoms not enjoyed on the Chinese mainland.

The semi-autonomous city is governed under that "one country, two systems" deal, but there are fears that freedoms are being eroded by increased influence from Beijing.

The Hong Kong government kicked off a promotional campaign to sell the vote plan after its launch but Leung and his deputy, Carrie Lam, were drowned out by protesters as they visited a middle-class district late Wednesday.

Protesters booed the pair and blocked their path with yellow umbrellas, a symbol of the democracy movement.

"Yesterday during the district visit... there were some hecklers who kept using loud voices and quite uncivilised words to try to speak over others," Leung told reporters Thursday.

"It's not democratic behaviour," he said. "We don't want to see such scenes at every district visit."

- 'Utter capitulation to Beijing' -

Currently the city's leader is chosen by a 1,200-strong election committee.

Beijing has promised universal suffrage for the 2017 vote, but has said that candidates must be approved first by a nominating committee.

"The central government consistently supports efforts to advance the democratic development" in the territory, Beijing's Hong Kong and Macau Affairs Office said on Wednesday, according to state news agency Xinhua.

Pro-democracy lawmakers have vowed to block the roadmap when it goes to a vote in Hong Kong's legislature in the coming months - which justice secretary Rimsky Yuen said would deprive citizens of a chance to vote.

Civic Party legislator Kwok Ka Ki called the government "irresponsible" and said that the reform package "in no way" gave Hong Kong people a real choice.

"We will be very cautious in making sure the people can get the real message instead of receiving a lot of fake messages and lies told by the government," he told AFP, saying that the opposition campaign would launch Sunday.

Human Rights Watch said the screening of candidates would violate the International Covenant on Civil and Political Rights and its China director Sophie Richardson described the election plan as an "utter capitulation to Beijing".

"The right to vote and the right to stand for election are fundamental human rights," she said.

"That the Hong Kong authorities are denying half that equation is a rejection of international law and of the promise of democracy for the citizens there."