After Beheading, Extremists Threaten Iraq's Interim Leader

"If half of what is attributed to him is true, then he is the most significant terrorist in Iraq at this time," the senior U.S. military official said of Zarqawi.

The statement attributed to Zarqawi, widely reported here on Arabic-language television networks, appears likely to encourage that view among Iraqis, many of whom have expressed reluctance to believe that their countrymen could be behind the suicide car bombings.

Weheb Hassan, 32, a crane operator, said he believed that the Bush administration was not unhappy with bombings such as Wednesday's because it does not really want to leave Iraq, with its oil reserves and strategic location for future military bases.

"As long as the Americans stay, the explosions will continue, whether they transfer sovereignty or not," he said. "They don't want the situation to stabilize."

An Iraqi soldier was killed by another roadside bomb in Mosul, about 215 miles north of Baghdad, a day after the killings of the dean of the college of law at Mosul University and her husband. Two policemen were shot to death in a drive-by shooting near Ramadi, 60 miles west of Baghdad, authorities reported, and in the far south of the country, two women who worked for the British military in Basra were shot as they drove home Tuesday evening.

Also, efforts by Shiite Muslim religious and political leaders to draw defiant cleric Moqtada Sadr and his followers into the political process suffered a setback. A spokesman for Sadr said the cleric would not participate in a national conference scheduled for next month unless its formula for representing Iraq's diverse political and ethnic currents was changed.

"After many discussions among ourselves, Moqtada Sadr's office announced it will not be able to attend the national conference session, for many concerns," said Ahmed Shaibani, a Sadr spokesman in Najaf, a Shiite holy city about 90 miles south of Baghdad. "One of the most important is the procedure adopted for representing different people."

Fuad Masoum, a Kurd who is organizing the conference, said he had not yet sent out formal invitations. The national conference has set as its goal choosing a body similar to a legislature that would monitor the interim government and help organize elections planned for next January.

Special correspondent Huda Ahmed Lazim contributed to this report.