Al Qaeda leader Osama bin Laden accused the United States of plotting to take control of Iraq's oil and urged Iraqis to reject efforts to rebuild a US-backed national unity government.
In a statement posted on the Internet yesterday, the militant leader said Washington wanted to build military bases in the country and dominate the region.
Bin Laden urged Iraqis to reject a plan which he said meant "to give the Americans all they wish of Iraq's oil" and said those who take part in a unity government would be turning their backs on Islam.
He urged Iraqis not to join counter-insurgency patrols -- predominantly Sunni Arab tribal police funded by the US military to fight al Qaeda and reduce violence -- and criticised the Saudi government for backing US policies in Iraq.
"The government of Riyadh is still playing its wicked roles," said the Saudi-born bin Laden.
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," the official said.
"The rhetoric as reported seems in keeping with well-worn al Qaeda themes on Iraq."
Earlier yesterday, 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.