Throughout March, Chen Lei's telephone did not stop ringing. A real estate agent in Shanghai's Songjiang district, a section of the city bursting with new property developments, he could barely keep up with the inquiries from would-be buyers.

For the past 10 days, the phones have been crazy again but this time the questions are different. “We have had lots of calls from buyers who ask us if they can cancel the deals they have made,” he says. “They think they will be barred from getting a mortgage.”

Over the past two weeks, the Chinese government has been rolling out an aggressive campaign to squeeze speculative buyers out of a property market that many analysts fear is close to a bubble. Almost every day a new administrative measure has been announced – raising the required deposit and interest rate on mortgages for second homes, telling local banks to avoid lending money for third homes and making it harder for people not resident in a city to get a mortgage there.