Alan Greenspan, the United States central banker, has warned that the US residential property market is at risk of crashing, if Americans continue to force property prices ever higher.

It is the strongest warning yet from the Federal Reserve Chairman, whos comments sent share prices falling on Wall Street, at one point knocking 66 points off the Dow Jones industrial average.

In a pre-retirement speech, Mr Greenspan said that people were not allowing for the risk of price falls. He said "history had not dealt kindly" with investors who kept ignoring risks.
Mr Greenspan said that the US house-price spiral had become an economic imbalance, threatening stability like the countrys trade gap or its budget deficit.