Joshua Wong, the teenage face of Hong Kong's pro-democracy movement, said Saturday he has ended a four-day hunger strike designed to force the government into further talks on political reform.

"Under the strong urging of the doctor, I have stopped the hunger strike," Wong, who had not eaten in 108 hours, said on his Facebook and Twitter feeds.

The 18-year-old said he felt "extreme physical discomfort, dizziness and weakness in the limbs".

"Even if I stop the hunger strike, it doesn't mean that the Hong Kong government can ignore our demands," Wong said.

Wong and two young female members of his Scholarism student group announced the "indefinite" hunger strike after Sunday, one of the worst nights of violence to hit the demonstrations.

Wong's announcement came after fellow hunger striker Isabella Lo announced she would stop the hunger strike on Friday, days after two others joined in the strike.

Student-led demonstrators are demanding free leadership elections for the semi-autonomous Chinese city, with the main protest camp continuing to block a long stretch of a multi-lane highway in central Hong Kong.

China's communist authorities insist that candidates for the 2017 vote must be vetted by a loyalist committee, which the protesters say will ensure the election of a pro-Beijing stooge.

Before Wong called off the strike, the government said it would not allow a hunger strike to affect its decision making.

"As a government we won't accept any illegal actions...or actions like a hunger strike to convince us to make any concessions," Secretary for Constitutional and Mainland Affairs Raymond Tam told reporters.

The rallies for fully free leadership elections, which are in its third month, drew tens of thousands at their height, but numbers have dwindled as public support for the movement has waned.

One prominent protest leader said the students would decide "within a week" whether to leave two remaining camps in the center of the southern Chinese city after authorities cleared a third last week.