In an audiotape broadcast by the Qatar-based Al-Jazeera satellite channel on Thursday, Osama 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 start of the Iraq war.
'Our enemies did not take it (Palestine) by negotiations and dialogue but with fire and iron. And this is the way to get it back,' he said.
On Wednesday, an Islamist website had issued another Osama recording which threatened the European Union with grave punishment for the publication of cartoons mocking Islam's Prophet Muhammad.
In that recording, Osama said the drawings were part of a 'crusade' against Muslims in which Pope Benedict was involved.
The chief Vatican spokesman, Rev Federico Lombardi, rejected those accusations as 'totally unfounded', noting the Pope has repeatedly criticised the cartoons, which were first published in European newspapers in 2006 and republished by Danish papers last month.
Italian security officials said they were examining the new tape and its impact on the Pope.
US officials said the Central Intelligence Agency was confident that the voice on the tape was that of the fugitive leader of Al-Qaeda, blamed for the Sept 11, 2001 attacks on the United States.
REUTERS