Brown laid the blame at Opec's feet

On BBC's Newsnight programme, Opec's acting head said the price rise was not the fault of producers, who had accelerated output in recent years.

Claims that demand had outstripped supply, Opec said, were not matched by industry figures.

Opec said the call from the Chancellor for a global solution was "welcome".

But it said that everyone, producers and consuming nations, had to do their part to solve the problem.

"The facts are known. Supply has been able to cope with the demand. I find it surprising to say that demand is outstripping supply. That is not so," Adnan Shihab-Eldin, acting secretary general of Opec told the BBC.

We are still looking for the stability point and hopefully it will not be too long Opec spokesman

The chancellor said at the weekend that Opec had failed to respond quickly enough to the surging demand for oil from China and called on it to increase supplies.

But Opec fears oversupply could cause oil prices to collapse.

It said increased investment meant oil prices would have to stay above at least $40 a barrel. But it agreed that the ideal price range would be somewhere between $40 and $60 a barrel.