Random price increases by owners of existing homes have dampened local buying momentum in May, with some areas in Shanghai suffering a double-digit drop in sales, two of the city's largest estate agencies reported yesterday.

Across the city, the used housing market seemed largely stable compared to April with transaction volume basically flat, they said.

"We've noticed a sales declines - about 10 percent monthly - in some of the city's residential communities after random price increases by home owners," said Yoyo Yu, a marketing official with Shanghai Centaline Property Consultants Ltd. "Such a scenario seemed to be particularly notable in communities that are rather popular with end-users instead of investors."

In western Zhongshan Park in Changning District, for instance, about half of the home owners have raised their prices in May, with the majority now asking for 5 to 10 percent above their original prices, according to Huang Yayan, a Centaline branch manager in the area.

In Putuo District's Caoyang, there was at least a 10 percent drop in sales of existing homes in May from a month earlier due to the same reason.

The owners usually have several apartments for sale and do not need money urgently, Huang said.

Eric Luo, a researcher with Century 21 China Real Estate, also said that it has become more common for owners to seek a price increase of up to 10 percent over the past month especially in the medium- to low-end markets.

In Songnan of Baoshan District, sales of existing houses plunged 20 percent in May after the number of home seekers tumbled 30 percent last month, according to Shuai Zhenghua, a Century 21 branch manager in the area.