Affected by more than five months of relentless anti-government protests, Hong Kong has officially fallen into recession. According to the city's Financial Secretary Paul Chan, it is unlikely that Hong Kong will achieve annual economic growth this year.

"The blow to our economy is comprehensive," he said in a blog post on Sunday, adding that figures of a preliminary estimate for GDP (gross domestic product) on Thursday would show two successive quarters of contraction - the technical definition of a recession.

"The government will be announcing its advance estimates for the third quarter on Thursday. After seeing negative growth in the second quarter, the situation continued in the third quarter, meaning our economy has entered technical recession," Chan wrote.

"It seems it will be extremely difficult for us to reach full-year economic growth of 0 to 1%. I would not rule out the possibility that the full-year economic growth will be negative."

On Sunday, protests continued with black-clad and masked demonstrators setting fire to shops and throwing petrol bombs at police who responded with tear gas, water cannon and rubber bullets, a Reuters report said.

In the 21 weeks of protest, shops and businesses including banks, particularly those owned by mainland Chinese companies have been torches and the city's metro system MTR Corp has been vandalised.

The former British colony that returned to Chinese rule in 1997 under a "one country, two systems" formula was intended to guarantee freedoms not seen on the mainland. While protesters are angry over increased interference from Beijing, mainland China denies these claims and has accused foreign governments of stirring up trouble.