Al-Qaeda's deputy chief Ayman al-Zawahiri yesterday claimed global warming was helping militant Islamic extremism.

Terror mastermind Osama bin Laden's deputy also launched an astonishing attack on Iran in a two-hour audiotape posted on an Islamic militant website.

He said global warming reflected "how criminal, brutal and greedy the Western Crusader world is, with America at the top".

The Egyptian surgeon accused Shiite Iran of trying to discredit the Sunni al-Qaeda terror network by spreading a conspiracy theory that Israel was behind the September 11 attacks.

Al-Zawahiri said: "Iran's aim is clear - to cover up its involvement with the US in invading Muslim homes in Afghanistan and Iraq."

The European commission is backing away from its insistence on imposing a compulsory 10% quota of biofuels in all petrol and diesel by 2020, a central plank of its programme to lead the world in combating climate change.

Amid a worsening global food crisis exacerbated, say experts and critics, by the race to divert food or feed crops into biomass for the manufacture of vehicle fuel, and inundated by a flood of expert advice criticising the shift to renewable fuel, the commission appears to be getting cold feet about its biofuels target.

Britain has set its own biofuels targets, which saw 2.5% mixed into all petrol and diesel fuel sold on forecourts in the UK this week. The government wants to increase that to 5% within two years, but has admitted that the environmental concerns could force them to rethink. Ruth Kelly, transport secretary, has ordered a review, which is due to report next month.

A commission source indicated that the EU executive would not object if European governments ordered a U-turn.

"This is all very sensitive and fast-moving," said a third commission official. "There is now a lot of new evidence on biofuels and the commission has become a prisoner of this process."

The target is being strongly criticised by the commission's own scientific experts and environmental advisers to the EU.

"The policy may have negative impacts on soil, water, and biodiversity," said Professor Laszlo Somlyody, who led a team of climate scientists analysing the policy for the Copenhagen-based European Environment Agency, which advises the EU. "This can lead to serious problems," he told the Guardian.

His report, published last week, calls on Brussels to freeze its biofuels policy because of the potential risks to the environment. "The over-ambitious 10% biofuel target is an experiment whose unintended effects are difficult to predict and difficult to control," the scientists found.

In March last year, European leaders sought to seize the global moral high ground by backing the commission's climate change package aimed at making Europe the world's first low-carbon economy. In January, the commission fleshed out the details of the measures, based on a carbon trading scheme which is to supply the bulk of the cuts in greenhouse gases.

But since then there has been a torrent of expert reports citing biofuels as part of the climate change problem.

This week, Jean Ziegler, the UN's rapporteur on the right to food, dubbed biofuels "a crime against humanity" because they allegedly divert food from the poor to provide fuel for the rich.

"The diversion of crops to fuel can raise food prices and reduce our ability to alleviate hunger," warned a 2,500-page analysis of global food trends from UN agricultural scientists.

Duffy asked Marohasy: "Is the Earth stillwarming?"

She replied: "No, actually, there has been cooling, if you take 1998 as your point of reference. If you take 2002 as your point of reference, then temperatures have plateaued. This is certainly not what you'd expect if carbon dioxide is driving temperature because carbon dioxide levels have been increasing but temperatures have actually been coming down over the last 10 years."

Duffy: "Is this a matter of any controversy?"

Marohasy: "Actually, no. The head of the IPCC (Intergovernmental Panel on Climate Change) has actually acknowledged it. He talks about the apparent plateau in temperatures so far this century. So he recognises that in this century, over the past eight years, temperatures have plateaued ... This is not what you'd expect, as I said, because if carbon dioxide is driving temperature then you'd expect that, given carbon dioxide levels have been continuing to increase, temperatures should be going up ... So (it's) very unexpected, not something that's being discussed. It should be being discussed, though, because it's very significant."

Dreams of a white Christmas fell flat but a sprinkling of snow can be expected over much of the country during Easter.

Arctic winds are forecast to sweep across Britain and bring widespread frosts over the Easter weekend, with snow in eastern regions.

The prospect of a white Easter, traditionally one of the busiest times of the year on the roads, will give the Met Office the chance to test its new hazardous weather alert system.