Warnings on an overheated real estate sector are hardly new, but in Chengdu, bank regulators are taking a more assertive stance on the prices of commercial properties.China Banking Regulatory Commission officials in Sichuan Province have asked to review data on the value of collateral for the commercial property sector in the provincial capital of Chengdu.The request represents the first time the CBRC has asked for information on the collateral put down for commercial property, largely in the form of land and buildings.An employee at a local bank said banks have already submitted the data requested but the results have not been made public.The same bank employee said if the value of the collateral for the loan is lower than 30 percent of what it was assessed at, the loan itself will be categorized as non-performing.Government data shows that the city of Chengdu is suffering from an oversupply of commercial property, especially in office buildings.In the first quarter of this year, Chengdu's vacancy rate for office buildings hit 40.8 percent, up from 35.9 percent at the end of last year, reported Jones Lang LaSalle.The vacancy rates are expected to rise even further with new space hitting the market this year.Concerns on the health of the property sector in Chengdu were raised by the CBRC as early as 2013, with the Sichuan branch publishing a report which stated banks broke rules by lending to developers without specifying what the money should be used for, among other violations.For Caixin Online, this is Diana Bates.