Kowloon Motor Bus has also applied to increase its prices, by 8.5 per cent. This means an average increase of 53 HK cents per passenger trip, the company said in November.

Ng Fung Hong, the city's only mainland beef distributor, raised its wholesale price by up to 6.76 per cent on December 22.

Consumer prices went up 3.7 per cent year on year in November, slightly down from 3.8 per cent in 2011, according to the composite price index.

And under proposals made last month, CLP Power will increase its tariffs by an average of 5.9 per cent while Hongkong Electric will charge 2.9 per cent more beginning from today, although both power companies have introduce rebates for low-volume users and CLP will impose penalties on heavy domestic users.

Social workers say low-income families are worried about the increasing prices, especially on rent and food, which make up a large part of their expenditure.

Mariana Chan Wai-yung, chief officer on policy research and advocacy at the Council of Social Service, said that faced with the higher prices, grass-roots and low-income households might spend less on food in order that they could afford their rent.

"I especially worry about the children," Chan said. "If they do not get sufficient nutrition long-term, it can affect their growth and development."

Sze Lai-shan, community organiser for the Society for Communication Organisation, a non-profit group, said: "People are telling us that they are experiencing price increases everywhere, particularly in rent and foodstuff. The salaries of low-income earners cannot catch up with the rate of inflation."

Sze said that to tackle these issues, the government should implement long- and short-term policies, including policies to subsidise rents, give cash to low-income families, and put new public housing flats on the market faster.