Residential property prices in Beijing's Central Business District rose 6.5 percent in the past week and demand for second-hand houses in some other areas is four times the supply, said the China Daily, citing brokerage Homelink.

It said a land parcel in Beijing, which was withdrawn from a public tender due to a lack of bidders only 15 months ago, was auctioned off Monday for a record US$585 million.

"The bidders have gone irrational. A bubble in Beijing's property market is definitely there," Pan Shiyi, one of the bidders that day and chairman of leading developer SOHO China, said after the auction, according to the report.

In Shanghai, developers of the luxury Tomson Rivers apartments, priced at over US$14,600 per square m2 (about US$1,360 per square ft2), sold at least 10 units in June, the report said.

That compared with sales of only four units since the project was marketed four years ago, it added.

In the southern city of Guangzhou, the downtown housing price reached US$1,600 per m2 in May, close to the record high of US$1,700 in October 2007, the report said.

"One thing we are concerned about is whether there is a new bubble being shaped," the report quoted Gu Yunchang, secretary general of the China Real Estate Association as saying. "The possibility of a bubble is pretty big."