"The United States administration incited certain Fatah linked groups to assassinate the head of Hamas [Ismail Haniyeh], because the Americans have sided with their friends in Fatah," al-Zawahiri said in an audio message posted early on Monday to Islamist websites.

"Everyone should know that the Egyptian regime supplied arms to Abu Mazen [Abbas's battle name] and wanted to send in 5,000 men trained in Cairo into the Gaza Strip to destroy Hamas," al-Zawahiri stated. "In this way, the world's most important popular movement would have come under US control," he continued.

"For this reason, we must help the Palestinian mujahadeen of Hamas - despite all the errors committed by their leadership", al-Zawahiri added. Al-Zawahiri had previously issued strong criticism of Hamas for its decision to enter democratic politics, and had warned its leaders that no good would come of the move. Now, he appears keen to mend the rift.

"All the mujahadeen of the world must stand beside them [Hamas] in the face of the new challenges that will come from the governments of Egypt and Saudi Arabia. They must understand that abandoning the will to impose Islamic (Sharia) law was a mistake - look at what happened Algerian and in Egypt," he said.

His Internet message comes as Palestinian politics is in turmoil after Abbas last week sacked the cabinet and appointed an emergency government based in the West Bank after Hamas militants seized control of the Gaza strip amid bloody factional fighting that claimed over 100 lives.

"This is nothing other than a phase of the Crusaders' Holy War against Islam," al-Zawahiri stressed. "Hamas previously claimed that it did not have relations with [al-Qaeda's leader] Osama bin Laden, but wanted to establish these with the West. But the European Union today backs Abu Mazen, who has betrayed your leaders, his nation and your religion."

"Has Bin Laden abandoned his religion?" al-Zawahiri asked.

Al-Zawahiri called on neighbouring countries to send money and weapons to the Gaza Strip, claiming that Israel wants to deploy 20,000 soldiers there. "Given the situation, we can only held the mujahadeen of Hamas. Their victory is the victory of Jihad in Palestine," he said.

"Giving them money and arms, thus breaking the emargo imposed by traitor Arab states is a religious duty incumbent on all those who live in states surrounding Palestine," al-Zawahiri concluded.