Premier Wen Jiabao said Saturday it was too early to loosen curbs on speculative property investment, state media reported, as authorities keep a tight grip over China's once red-hot housing sector.

Wen, who was inspecting an affordable housing project said government efforts to rein in runaway housing prices had been largely successful, the official Xinhua news agency said.

"But the controls over the real estate market are still in a critical period," Wen said in the port city of Tianjin, southeast of Beijing.

His comments come after Xinhua reported last month that China was studying new measures to beef up controls on the property sector, amid signs housing prices were bouncing back.

New home prices in 50 out of the 70 Chinese cities tracked by the government increased in July from June, latest official data showed. That represented a doubling from 25 in June.

The government has been tightening policies for more than two years. Measures include prohibitions on buying second homes, an increase in minimum down payments and the introduction of property taxes in certain areas.

Wen also said effectively increasing the supply of homes to the market would be important in consolidating the success in stabilising housing prices, Xinhua reported.

He also said China had begun work on more than 21 million affordable homes from 2009 to 2011, with almost half the total already built.