Hong Kong pro-democracy lawmakers said on Sunday they would "definitely" veto the government's planned political reforms after a last-ditch meeting with Chinese officials failed to reach any agreement.

The package unveiled in April for the semi-autonomous Chinese city would for the first time allow all voters to elect Hong Kong's next chief executive in 2017.

But critics deride the proposal as "fake democracy" because it sticks to a ruling by China that candidates must first be approved by a loyalist committee.

Beijing's restrictions, announced last August, sparked more than two months of mass rallies that brought main roads in parts of the city to a standstill late last year.

Democratic lawmakers said Sunday they had made no progress after meeting top Beijing officials in the southern Chinese city of Shenzhen.

The meeting was widely seen as the last chance for compromise before Hong Kong lawmakers vote on the political reform package in June.

It needs a two-thirds majority to pass and pro-democracy lawmakers make up more than a third of the legislature.

"We came here... trying to find a way out of the impasse," Civic Party leader Alan Leong told reporters after the four-hour meeting, which was attended by 14 out of 27 pro-democracy lawmakers as well as 40 pro-Beijing legislators and the city's current leader Leung Chun-ying.

"We are left with an unequivocal conclusion that the Central People's Government is not going to yield," Leong said.

"We are therefore left with no choice but to definitely veto the government proposal."

Wang Guangya, the director of the Hong Kong and Macau Affairs Office of the Chinese State Council or cabinet, said it was "unfortunate" that the democrats were uniting to stop the plan.

"The other side behaved like a bloc, holding on to their strict position... I don't think it's constructive or healthy," he said after the meeting.

Wang said lawmakers have a "historic responsibility" to cast their vote "with conscience".

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Before the meeting Wang had said that any election plan would have to stick to Beijing's ruling.

Another Beijing official, Li Fei, said the vote would test whether democrats are loyal to the principle of "one country, two systems" under which Hong Kong is ruled, local media reported.

Hong Kong was handed back to China by Britain in 1997 but is largely self-governing and enjoys freedoms not seen on the mainland.

Li also warned during the meeting that lawmakers could be "punished" by voters for vetoing the plan, the South China Morning Post reported on its website.

On Sunday afternoon around 1,000 protesters marched through central Hong Kong to commemorate China's bloody crackdown on pro-democracy protesters in Beijing's Tiananmen Square, ahead of the 26th anniversary on June 4.

Some wore yellow ribbons and carried yellow umbrellas, symbols of Hong Kong's democracy movement.

"We hope to have democracy in China so Hong Kong can get it too," said retiree Chow Ka-kong, 76.

A number of vigils will be held in Hong Kong on June 4.