Cairo: The leader of an Al Qaida-linked group in Iraq has threatened to launch an attack on Iran unless it stops supporting Shiites in Iraq.

In a new audiotape released on Sunday, Abu Omar Al Baghdadi gave Iranian leaders two months to severe ties with Iraqi Shiites or they would face a "severe war."

The 50-minute audiotape, which could not be independently verified, was posted on a website commonly used by militants.

US forces had earlier claimed to have killed Baghdadi, who said in the tape that his Sunni fighters have been preparing for four years to attack Shiite-dominated Iran.

Baghdadi also set a deadline for Sunnis and Arab countries doing business in Iran or with Iranians, telling them "not to take partnership with any Shia Iranian businessman; this is part of the two-month period."

Iraq's Shiite-led government is backed by the United States but is closely allied to Iran. The United States accuses Iran of arming and financing Shiite militias in Iraq, a charge which Tehran denies.

Baghdadi said his group was responsible for two suicide truck bomb attacks in May in Iraq's northern Kurdish region.