Osama bin Laden has urged Palestinians to use 'iron and fire' to end an Israeli blockade of Gaza, in a recording after the Vatican rejected accusations by the Al Qaeda chief of a 'new crusade'.

In an audiotape broadcast by the Qatar-based Al Jazeera satellite channel on Thursday, bin Laden urged Muslims to keep up the struggle against US forces in Iraq as a path to 'liberating Palestine'. The tape was released around the fifth anniversary of the US invasion of Iraq.

'My speech is about the Gaza siege and the way to retrieve it and the rest of Palestine from the hands of the Zionist enemy,' the Saudi-born militant said.

'Our enemies did not take it by negotiations and dialogue but with fire and iron. And this is the way to get it back.'

On Wednesday, an Islamist Web site had issued another bin Laden recording which threatened the European Union with grave punishment for the publication of cartoons mocking Islam's Prophet Mohammad.

In that recording, which coincided with the birthday of Islam's founder, bin Laden said the drawings were part of a 'crusade' against Muslims in which Pope Benedict was involved. The Vatican has rejected those accusations.

'These accusations are totally unfounded,' chief Vatican spokesman Rev. Federico Lombardi said. Italian security officials said they were examining the new bin Laden message and its impact on the Pope, who is preparing for busy Easter weekend celebrations.

'Obviously we can't ignore it but at this moment that doesn't mean the threat is being taken seriously,' said an Italian security source.

Bin Laden's message showed he regards Europe as fertile soil for Al Qaeda, especially at a time of tension between free speech and Muslim values, but is unlikely to signal an imminent attack, security analysts and officials said.

There is no evidence bin Laden's statements contain coded instructions to Al Qaeda operatives and he has no track record of delivering warnings immediately before an attack, they said.

Bin Laden said Europe would be punished for the cartoons, which were first published by a Danish paper in September 2005. The images ignited bloody unrest among Muslims when other newspapers around the world reprinted them the following year.

Last month, some Danish papers republished one of the cartoons in solidarity with the cartoonist after three men were arrested on suspicion of plans to kill him, sparking more anger.

'Your publications of these drawings - part of a new crusade in which the Pope of the Vatican has a significant role - is a confirmation from you that the war continues,' said bin Laden, addressing 'those who are wise at the European Union'.

US officials said the CIA was confident the voice was that of the fugitive leader of Al Qaeda, blamed for the September 11 attacks.-Reuters