A new audio message purportedly from Osama Bin Laden has urged Muslims to join the insurgency in Iraq as the best way to support the Palestinians.
The messages are the first since November
"The nearest jihad battlefield to support our people in Palestine is the battlefield of Iraq," the speaker said.
The message, aired on al-Jazeera TV, comes a day after the al-Qaeda leader threatened the EU over the reprint of a cartoon deemed offensive to Muslims.
The messages coincide with the fifth anniversary of the US invasion of Iraq.
BBC defence and security correspondent Rob Watson says they follow a familiar pattern, with Bin Laden touching on an issue he knows resonates with many Muslims
'Fire and iron'
In the second message in two days, the speaker dismissed attempts at reconciliation in the Middle East.
"Palestine cannot be retaken by negotiations and dialogue, but with fire and iron," he said.
The speaker said Arab leaders were accomplices in Israeli attacks on Gaza.
"The people of the blessed land should sense the great favour God has bestowed upon them and do what they should do to support their mujahideen brothers in Iraq," he said.
"It is a great opportunity and a major duty for my brothers the Palestinian emigrants [in Arab countries], between whom and jihad on the plains of Jerusalem a barrier has been built."
The message comes weeks after a major Israeli offensive in Gaza in response to militant rocket attacks. Some 125 people were killed, mostly Palestinian civilians.
Israel has not issued a response to the tape, with officials saying it never comments on Bin Laden statements.
Saeb Erekat, a Palestinian negotiator in the faltering talks with Israel, said the Palestinians and the international community had to prove al-Qaeda wrong.
"We have been pursuing peace through negotiations, and I believe the parties involved must make every effort to make the year 2008 a year of peace," he said.
It is not clear when the messages were recorded.
The authenticity of the first message was confirmed in the US by the CIA and White House.
"It can be said with a high degree of confidence that it is in fact the voice of Osama Bin Laden," a CIA official told Reuters news agency.
In a major speech on the fifth anniversary of the beginning of the war, US President George W Bush claimed what he called the "first large-scale Arab uprising against Osama Bin Laden" was taking place in Iraq.
He was referring to the "Awakening" councils - US-backed armed groups of former Sunni Arab insurgents - which are credited with driving back al-Qaeda-inspired groups from areas in central Iraq.
Bin Laden is believed to be in hiding in the rugged border area between Pakistan and Afghanistan.
Western intelligence sources continue to view him as a formidable opponent, our correspondent says, but they also argue al-Qaeda has had recent setbacks with its dramatic reversal of fortunes in Iraq and the killing and capture of several prominent leaders.