Hong Kong's unpopular leader Leung Chun-ying, who has been vilified by critics as a puppet of Beijing, said Friday he would not run again for office after a term marked by anti-China protests and political divisions.

Leung said he would step down at the end of his term in July for family reasons after speculation intensified in recent weeks over who would get the nod from Beijing for leadership elections in March.

Some pro-democracy campaigners predicted there would be public "euphoria" at the news, while analysts said the announcement had come as a surprise, just three months before the election in which Leung was widely expected to run for a second term.

Leung said Beijing had been "very supportive" and said he was not stepping down because of a lack of backing from China.

"The central government has always fully affirmed and had high opinions of my work," he said.

China has accepted Leung's decision, according to state news agency Xinhua.

Leung took office in 2012 as concerns were growing that Beijing was tightening its grip on the semi-autonomous city and his opponents have slammed him as a hardline leader overseeing the erosion of Hong Kong's freedoms.

His term has been one of political crises with massive pro-democracy rallies in 2014 bringing tens of thousands onto the streets calling for reform and for Leung to step down.

The failure of the protests to win any concessions left the city starkly divided between pro-establishment and pro-democracy camps and sparked an independence movement calling for the city to break entirely from Beijing.

China has expressed its fury over the movement, which it says is illegal and will damage Hong Kong's prosperity.

Last month two democratically elected lawmakers who support a split from China were barred from taking up their seats after an intervention from Beijing.

A group of more moderate pro-democracy lawmakers are facing a court case Thursday brought by the government which is also seeking to remove them from the legislature.

- Cautious celebrations -

Pro-democracy campaigner Joshua Wong, who led the 2014 rallies, said that while some people might celebrate Leung's decision, there were now fears that he would simply be replaced with another hardline leader.

The chief executive is chosen by a 1,200-strong committee of special interest groups weighted towards Beijing.

The mass "Umbrella Movement" rallies of 2014 were calling for that system to be overturned and for the leader to be chosen by the public.

Those protests were triggered after Beijing said Hong Kong could choose its own chief executive, but that candidates would have to be vetted.

"I think CY Leung not getting re-elected is of course a good thing... he has triggered lots of public discontent," Wong told AFP but added there needed to be broader fundamental changes.

"The problem is not about people, but that the system needs to be reformed," he said.

Pro-democracy lawmaker Claudia Mo also warned that campaigners should not be complacent.

"Whoever is chief executive is still going to be hand-picked by Beijing," Mo told AFP.

Analyst Joseph Cheng said that there had been speculation that Beijing had refused to back Leung as it had not signalled support.

"Normally we expect some signals from Beijing by this time," he said.

There are question marks over how much support Leung could rally from the pro-establishment camp after his rocky term. Beijing may want a stronger candidate, said analyst Edmund Cheng.

Leung only secured 689 votes of 1,200 in 2012.

"To assure that Beijing has better control of the current system, they may want to increase the legitimacy of the next chief executive, and they may want someone to get more (votes) than that," said Cheng, professor of government and international studies at Hong Kong Baptist University.

Leung said he was stepping down out of "responsibility as a father and a husband" and that it was not to do with his performance as leader.

Reports in local media have said that Leung's daughter Leung Chai-yan, 25, has been in hospital for more than a month, although the reasons are unclear.

His daughter hit the headlines in 2015 after slapping her mother in public and announced she was leaving home because of explosive rows with her parents.

China's spokesman for Hong Kong and Macao Affairs told Xinhua: "We express our deep regret that Leung has decided not to pursue another term due to family reasons, and we respect his decision."

Only one candidate has declared they are running for the leadership so far -- retired judge Woo Kwok-hing.

"With Mr. Leung not running, I hope society will be less divided," Woo said Friday.