Al Qaeda leader Osama bin Laden accused Washington of plotting to take control of Iraq's oil and urged Iraqis to reject efforts to rebuild a US-backed national unity government there.
The militant leader also vowed in an audio recording posted on the internet on Saturday to expand its jihad to liberate all Palestinian land and said his group will never recognise Israel.
"America seeks, alongside its agents in the region, to create an allied government ... that would accept in advance the presence of major US bases in Iraq and give the Americans all they wish of Iraq's oil," he said.
The Saudi-born militant said the envisaged Iraqi government was also meant to help Washington "fully dominate" the region with help from allies such as Saudi Arabia.
"The government of Riyadh is still playing its wicked roles," he said, describing Saudi Arabia's King Abduallah as the United States' "chief agent".
Referring to a Saudi push in February to help Palestinian rivals agree a unity government which fell apart in June, he said Riyadh was part of a scheme to lure Islamist Palestinian militant group Hamas away from its jihadist roots.
"I assure our kin in Palestine especially that we shall expand our jihad ... We will not recognise a state for the Jews over even an inch of Palestinian soil," he said.
Bin Laden did not mention accusations that Al Qaeda was behind Thursday's assassination of Pakistani opposition leader Benazir Bhutto. A Qaeda-allied militant leader there has denied involvement.
But bin Laden took a swing at Sayyed Hassan Nasrallah, the leader of Iran-backed Lebanese Hezbollah guerrillas, for accepting the expansion of a United Nations force in Lebanon after the Shi'ite group's war with the Jewish state in 2006.
The peacekeepers dispatched to Lebanon after the war were there to "protect the Jews", said bin Laden, whose group belongs to a school of Islam that sees Shi'ite Muslims as heretics.
Bin Laden said Washington was planning to form a new Iraqi national unity government and warned that those who took part would be turning their backs on Islam.
Sunni Arabs pulled out of Prime Minister Nuri al-Maliki's Shi'ite-led government earlier this year, accusing it of being too sectarian.
He also urged Iraqis not to join counter-insurgency patrols -- predominantly Sunni Arab tribal police funded by the U.S. military to fight al Qaeda and reduce violence -- and criticised the Saudi government for pro-US policies in Iraq.
White House spokesman Tony Fratto said in a statement the tape was a reminder of al Qaeda's continued activities in Iraq.
"This is a reminder that the aim of al Qaeda in Iraq is to block democracy and freedom for all Iraqis. It also reminds us that the mission to defeat al Qaeda in Iraq is critically important and must succeed," Fratto said.
A US counter-terrorism official said Washington was aware of the recording and was looking into it: "There has never been a fake bin Laden tape, so there really wouldn't be any reason going in to believe it would be anything other than authentic."
Earlier on Saturday, Iraq's Interior Ministry said Sunni Arab al Qaeda's influence in Iraq had dramatically fallen, with 75 per cent of its networks and 70 per cent of its activities having been eliminated. (Reuters)