China's economy, the chief source of new demand in world energy and metal markets, expanded by 9.1 per cent in the quarter to the end of September, marking the third consecutive quarter of slowing growth as Beijing reaffirmed its resolve to guard against any economic rebound.

Zheng Jingping, spokesman for the National Statistical Bureau, said China needed to ensure that a speculative property bubble did not inflate in the big cities and added that tight energy supplies, high prices and the possibility of a fresh boom in investment meant that administrative controls on the economy would not be loosened.

"We cannot treat these problems lightly," Mr Zheng said.

"We should further enhance and expand the achievements of macro-control to guard against a rebound of those problems," he added.

The price of property, a driver of demand in the overheated steel, cement and aluminium sectors, rose rapidly in the first nine months in the largest 35 cities in China.

Average property prices climbed 13.4 per cent from the same period a year ago.

"The rising property prices are not a good thing after all and we should pay close attention to the trends to prevent prices from rising too rapidly and prevent a speculative bubble," Mr Zheng said.

Overall though, Chinese policymakers were expected to be comforted by the third-quarter figures, which show a controlled year-on-year slowdown from 9.8 per cent in the first quarter and 9.6 per cent in the second.

In the first nine months the economy expanded at an official 9.5 per cent.

Beijing implemented a series of macro-economic controls in April aimed at taming excessive investment in some sectors, easing pressure on an overloaded transport and electricity network and restraining upward pressure on prices. - (Financial Times Service)