HONG KONG (AFP) - Billionaire Hong Kong businessman Li Ka Shing called for the divided city to unite and dismissed the idea it would ever be independent from China on Thursday (March 17).

Li, 87, was speaking after his flagship CK Hutchison Holdings posted a net profit of HK$31.2 billion (S$5.5 billion) for 2015, beating analysts' estimates following a sweeping reshuffle of his business empire.

Although Li's firms are prospering, he said Hong Kong's business environment is at its worst for 20 years.

"There is not really a sector that is doing well... Property sales and the retail sector are doing worse than during Sars," he said, referring to the disease outbreak in 2003.

Hong Kong is suffering due to a weak global economy and slowdown in China, but Li warned political instability could also dent its fortunes.

Young protesters in the semi-autonomous city are frustrated at a lack of dialogue with Beijing on political reform and say they will use violent tactics to force change.

February saw running battles between protesters and police and young residents are increasingly calling for independence from China.

"People engaged with politics need to learn that regardless of political affiliations, people should not do anything that is harmful to Hong Kong... or our competitiveness could go backwards," said Li.

"If we stay united, there are many things that we can do." He said independence was out of the question.

"Hong Kongers would not agree we are qualified to become independent. Hongkongers would not (even) like to say such words," he said.

The city was handed back to China by Britain in 1997 under a deal that protects its way of life for 50 years, but there are fears Beijing is tightening its grip.

The detention in China of five Hong Kong booksellers, known for selling salacious titles critical of Beijing, has exacerbated concerns.

Li has himself come in for criticism on the mainland after selling off assets there, with the People's Daily, a mouthpiece for China's Communist Party, blasting him as "ungrateful".

He has defended his business decisions which have seen him snap up European companies and took a conciliatory tone Thursday, dismissing concern over China's slowdown.

"As a vast country with 1.3 billion population it is still growing at 6.5 per cent, which is not easy to achieve," he said.

CK Hutchison Holdings controls assets in telecoms, utilities, ports and other industries in over 50 countries.

Thursday's full-year earnings report gave results adjusted to show what they would have been if the company's June revamp had occurred at the beginning of 2015.

The adjusted results showed net profit for 2015 had slipped eight percent to HK$31.2 billion compared to the previous year, but beat the HK$30.9 billion average analysts' estimate from Bloomberg.

Strong telecoms and savings from the revamp had outweighed losses in the energy sector due to weak oil prices, Li said.

In the reshuffle, Cheung Kong changed its name to CK Hutchison Holdings, while property-related business came under the control of CK Property, a newly listed company.

Hutchison Whampoa, trading on the city's bourse since 1978, was delisted.

Net profit for Cheung Kong Property in 2015 was HK$17.1 billion, Thursday's report said.