Hong Kong protests: China strongly backs leader CY Leung

China's state media have strongly backed Hong Kong Chief Executive CY Leung, praising his performance while condemning protests as "chaos".

The support in Communist Party paper People's Daily comes as student activists threaten to occupy government buildings if Mr Leung does not resign.

Police and government have again called on protesters to disperse.

The protesters are angry at China's plan to vet candidates for polls in 2017, saying they want full democracy.

On Wednesday China's Foreign Minister Wang Yi also warned against "illegal" protests and foreign interference.

'Disrespecting the law'

The People's Daily is the Chinese Communist Party's official newspaper. In a front-page editorial on Thursday, it praised Mr Leung's handling of the situation so far.

Protesters have been sleeping on roads around government buildings for several days

There is a heavy police presence outside the office of Chief Executive CY Leung

"The central government is full of confidence in Chief Executive Leung Chun-ying [CY Leung], and is completely satisfied with his performance," it said.

Beijing "will thus continue to strongly support Mr Leung's leadership of Hong Kong's legal administration as well as the police's handling of illegal activities", it added.

People's Daily also carried on its website a comment piece from another newspaper which stated: "Hong Kong has for many years enjoyed peace and harmony. It now sees the emergence of this embarrassing chaos, and the root cause lies with a few people who are disrespecting the law."

"Chaos denies Hong Kong residents their prosperity, goes against their wishes, and is not what all Chinese people wish to see or what we can tolerate."

Beijing's support of Mr Leung follows repeated calls by protesters for his resignation.

Juliana Liu, BBC News, Hong Kong

The senior Chinese leadership has set out clear limits on who can run for the position of chief executive, Hong Kong's top leader, in 2017.

The rules make it virtually impossible for anyone not trusted by the Chinese government to stand for election.

As a result, the protesters accuse Beijing of reneging on decades of vows to give Hong Kong people genuine democracy.

But although there is widespread anger that Beijing may have violated the spirit of the agreements it has made, there is intense debate over whether it has violated the letter of the law.

Read more: Did China go back on its promises?

Overnight, several thousand protesters massed outside his office, where there was a significant police presence.

Large numbers of protesters came out on to the streets on Sunday, when supporters of the Occupy Central pro-democracy movement joined student demonstrations. More people joined after police used tear gas on protesters.

Since then, protesters have been occupying at least three sites in the territory, in the Central business district, Causeway Bay and Mong Kok. A fourth site opened up at Canton Road on Wednesday.

Lester Shum, the vice-secretary of the Hong Kong Federation of Students, has called on Mr Leung to resign by Thursday night.

"Otherwise, we will announce an escalation of our movement, including occupying or surrounding different government buildings," he said.

Both the Hong Kong government and the police on Thursday reiterated their call to protesters to disperse.

Police spokesman Steve Hui told reporters that if protesters surrounded and occupied Mr Leung's office building in Central, this would cause public safety problems. "The police will not stand by and watch. We will decisively uphold the law," he said.

When asked if tear gas would be used, Mr Hui said the police would monitor the situation and would use "appropriate force if necessary", reported RTHK.

The South China Morning Post is reporting confrontations between the police and protesters outside the building.

The Hong Kong government said the protesters were conducting a "siege" and if it continued, government and police operations would "be seriously affected".

"This will eventually affect social order and the provision of government services to the public and society," it said, adding that 3,000 government officials were due to return to work on Friday.

Chan Kin-man of Occupy Central has urged the students to be peaceful, but also called on Mr Leung to quit.

Speaking in Washington on Wednesday, China's Foreign Minister Wang Yi said the protests were an "internal affair" for China. Hong Kong authorities had "the capability to properly handle the current situation", he said.

In other developments:

• Mainland authorities have suspended bookings for tour groups to Hong Kong, the South China Morning Post reported

• On Wednesday, several rallies supporting the protests took place around the world, including in Taiwan, London and Macau

• Rights groups say some mainland-based activists have been detained

Several reports, citing unidentified Hong Kong sources, suggest the authorities plan to wait, hoping the protest campaign will lose momentum.

Hong Kong democracy timeline

• 1997: UK gives Hong Kong back to China under a 1984 agreement giving it "a high degree of autonomy" for 50 years

• 2004: China says it must approve any changes to Hong Kong's election laws

• June-July 2014: Pro-democracy activists hold an unofficial referendum on political reform. Both sides hold large rallies

• 31 August 2014: China says it will allow direct elections in 2017 but will pre-approve candidates

• 22 September 2014: Student groups launch a week-long boycott of classes

• 28 September 2014: Occupy Central and student protests join forces and take over central Hong Kong

• 2017: Direct elections for chief executive due to take place

• 2047: Expiry of current agreements

Q&A: Hong Kong's democracy controversy