Alan Greenspan, the former US Federal Reserve chairman blamed in some quarters for not doing enough to prevent the financial crisis, has predicted that more crashes are inevitable.

Speaking a year after the collapse of Lehman Brothers, the US investment bank, Mr Greenspan said: "The crisis will happen again but it will be different. They [financial crises] are all different, but they have one fundamental source," he told the BBC. "That is the unquenchable capability of human beings when confronted with long periods of prosperity to presume that it will continue."

He added that, although the current crisis was triggered by the trade in US sub-prime mortgages, any factor could have been the catalyst. "Something sooner or later would have emerged", Mr Greenspan said.

The former US central bank chief claimed that the world's financial institutions should have foreseen the looming crisis. "The bankers knew that they were involved in an under-pricing of risk and that at some point a correction would be made," he said. "I fear too many of them thought they would be able to spot the actual trigger point of the crisis in time to get out."

He also warned that Britain would be harder hit than the US by the current recession and collapse in world trade.

"Obviously we've both suffered very considerably but ... Britain is more globally oriented as an economy and the dramatic decline in exports globally and trade generally following the collapse of Lehman Brothers had dramatic effects in the financial system of Britain," Mr Greenspan said. "It's going to take a long while for you [Britain] to work your way through this."

But he cautioned that the path to recovery should steer clear of protectionism as applying strict regulations could hamper recent developments that have opened up global trade. "The most recent endeavour to re-regulate is a reaction to the crisis. The extraordinary impact of these global markets is making a lot of financial people feeling they have lost control. The problem is you cannot have free global trade with highly restrictive, regulated domestic markets."

Mr Greenspan also brushed off suggestions that he bears a degree of responsibility for the problems gripping the global economy. "It's human nature, unless somebody can find a way to change human nature, we will have more crises and none of them will look like this because no two crises have anything in common, except human nature."

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