According to the real estate service provider Century21, in September alone, Shanghai auctioned 18 commercial land parcels for 40.3 billion yuan, which registered a record high so far this year in terms of both area and revenue.

It was also the sixth straight month the city witnessed a monthly land sales income of more than 10 billion yuan.

The record level was largely because of deals over prime land in Shanghai's downtown Xujiahui area, which was purchased by Hong Kong developer Sun Hung Kai Properties for 21.77 billion yuan on Sept 5. It became the nation's most valuable plot since 2010.

Among the 18 auctions, eight land parcels were sold at a deal price twice or even higher compared with the trigger price, among which four were located in the Pudong area.

The 10 major property developers in China, including China Vanke Co and Evergrande Real Estate Group, have paid a total of 244.7 billion yuan at land auctions so far this year - 50 percent more than the same period last year and 11 percent more than the whole of last year.

But experts also warned such surging land prices may not be sustainable.

Huang Yu, deputy head of the China Index Academy, said policies would be more prudent in the fourth quarter, with property tax and land reform likely to be enacted.

Meanwhile, because the central government is calling for controls on prime land, there will be fluctuations in land prices in the last quarter of this year, he said.