The People's Bank of China, the central bank, said it has called on commercial banks to tighten loans to property developers in what it described as an effort to encourage more efficient land use.

The central bank said in a statement on its website that landbanking loans, where already acquired property is used as collateral for bank financing, should not be extended for more than two years.

It also restated its curbs on bank loans being used directly for land purchases by developers.

The statement on the central bank website, though posted on August 27, was dated from late last month. The bank did not give an explanation.