HOUSE prices in some parts of Sydney have almost halved as battling borrowers struggle to keep up with increasing interest rates.

The falls - in Sydney's west, the Hills district, and Sutherland Shire - are far steeper than previously thought, and show the devastating effects of the RBA's rate-hiking spree.

In the past six months, 30 homes across Sydney have been sold for at least $100,000 less than was paid at the height of the property boom, many as a result of distressed mortgagee sales.

One property in Bankstown, bought for $500,000 in August 2005 sold in February for $215,000 - a loss of $285,000.

Several other properties in Sydney's west have recently been sold for losses of more than 30 per cent.

Sutherland Shire, which was thought to have escaped relatively unscathed, is now having prices plummet.

One property in Oyster Bay, bought for $1.09 million in December 2001, sold in March for $680,000, while a Caringbah apartment bought for $339,000 in June 2004 was sold for a loss of $104,000 last October.

"The Sydney housing market is in a bind - we have a shortage of housing and huge demand but that isn't going to stop prices declining further. I think we'll see prices fall by another 10 per cent this year - and that's without another interest-rate rise."