U.S. National Security Advisor Stephen Hadley says he can not confirm reports that terror leader Musab al-Zarqawi has been seriously wounded in Iraq.

But Mr. Hadley told U.S. television that Zarqawi heads a lethal network and his death would lead to a significant difference in the level of violence in Iraqi.

His comments came after London's Sunday Times  quoted an Iraqi doctor who says he treated Zarqawi at a hospital in Ramadi on Wednesday. The Times report says the doctor was debriefed by U.S. authorities on Friday.

The doctor said the terrorist was bleeding heavily when treated and left despite recommendations that he remain under hospital care.

Saturday, the U.S. military ended a week-long offensive against insurgents holed up near the border town of al-Qaim. Authorities said nine Marines and 125 insurgents were killed in the fighting.