Hong Kong's unpopular pro-Beijing leader Leung Chun-ying faced protests Wednesday as he spoke out against the city's independence movement in his final policy address.

Leung will step down in July after a four-year term marked by anti-Beijing rallies as fears grow that Chinese authorities are squeezing Hong Kong's freedoms.

Frustration at lack of political reform has sparked movements seeking self-determination or even independence for the semi-autonomous city, angering Chinese authorities.

As he struggled to start his speech due to heckling, some pro-democracy lawmakers held up signs depicting Leung as a monkey and calling him a "liar".

"As we benefit from the opportunities brought by the development of our country and the national policies in our favour, we must clearly recognise that Hong Kong is an inalienable part of our country," Leung said in the annual address.

"This is both a legal fact and an internationally recognised political reality, leaving no room whatsoever for Hong Kong to become independent or separate from the motherland in any manner," he added.

Residents must "safeguard national sovereignty, security and territorial integrity", said Leung, who did not mention any plans for kickstarting democratic reform in his speech, after a controversial Beijing-backed package was shelved following massive protests in 2014.

Joseph Cheng, a political scientist and pro-democracy activist, criticised Leung for sidestepping "basic issues" including his "political suppression of the opposition".

Answering reporters' questions, Leung said his government had worked hard to push political reform and that a minority had resisted.

He said people must accept Beijing's roadmap, which declared the public could vote for its leader, but only after nominees were vetted by an election committee.

Currently that committee -- which is largely made up of special interest groups skewed towards Beijing -- selects the leader with no public vote.

The Beijing-backed reform plan was dismissed as "fake democracy" by opponents and voted down in the legislature by pro-democracy lawmakers.

- Liberty and democracy -

Amnesty International Hong Kong last week said human rights were at their worst since the city was handed back to China by Britain in 1997, in the wake of the disappearance of five city booksellers known for publishing salacious titles about Chinese leaders, and interference by Beijing in a range of areas, from media to education.

The government has also been accused of a witch hunt after two pro-independence lawmakers were forced to give up their seats last year. Four more pro-democracy legislators face a judicial review into whether they should be disqualified.

However, Leung said the city still enjoyed a high degree of autonomy and pledged his government would "uphold Hong Kong's core values, including human rights, liberty, democracy, the rule of law and integrity".

Leung framed the city's economic strategy within Beijing's latest five-year plan and its One Belt, One Road initiative, which calls for constructing vast rail and infrastructure links connecting Chinese exporters to markets across Eurasia.

Around 100 protesters gathered outside the legislature, protesting over pension funds and workers' rights.

Wealth inequality and perceived cosiness between politicians and the business elite is driving discontent.

Leung promised 460,000 new housing units in the next decade and a rise in the minimum wage. However he rejected the idea of a universal state pension.

The city's election committee will choose a new leader for Hong Kong in March, with Leung's tough deputy Carrie Lam tipped to be Beijing's favourite.

Critics fear she will be another hardliner, but Lam said Monday she wanted to heal divisions in society.