Ian Shepherdson, from High Frequency Economics, told the conference in Paris that the crisis was a super-cyclical event not seen since the 1930s, and damage to the world's banking system will take years to work through. The earliest trend growth may resume is 2012 or 2013. "Working out that catastrophe is going to take years," he said. "It will be worse than many past crises because the banks are in such bad shape." Overall global bank losses since 2007 are around $1.1tr.

Shepherdson's remarks came in contrast to the general tone of the conference, where 68% of real estate specialists expressed the view in an electronic vote that investment should pick up this year. While some 44% predicted a W-shaped crisis - a further dip before sustainable improvement sets in - another 36% favoured a U shape - with a relatively smooth and quick recovery.

Shepherdson identified the main causes of the crisis as the US Federal Reserve's rates cuts to 1% at the beginning of the last decade. "This was a gigantic mistake, and it led to a credit boom in a truly insane fashion," he said. Most excess credit went into residential mortgages in Anglo-Saxon countries, specifically the US, and the bubble burst has produced home loan delinquency rates of about 30%. Recent figures show 5m American households own homes with values now at 75% or less than their mortgage debt--so that a further mass of foreclosures must still come. Turning to commercial real estate, he said, "America is now becoming the land of abandoned malls."