In a half hour audio file entitled "They plotted yet God too was plotting," Abu Omar al-Baghdadi also named the other insurgent groups in Iraq that al-Qaida was fighting and promised new attacks, particularly against the minority Yazidi sect.

"We are calling for the assassination of cartoonist Lars Vilks who dared insult our Prophet, peace be upon him, and we announce a reward during this generous month of Ramadan of $100,000 for the one who kills this criminal," the transcript on the Web site said.

The al-Qaida leader upped the reward for Vilks' death to $150,000 if he was "slaughtered like a lamb" and offered $50,000 for the killing of the editor of Nerikes Allehanda, the Swedish paper that printed Vilks' cartoon of the Prophet Muhammad with a dog's body on Aug. 19.

Vilks said from Sweden he believed the matter of his cartoons had been blown out of proportion.

"We have a real problem here," Vilks told The Associated Press by telephone. "We can only hope that Muslims in Europe and in the Western world choose to distance themselves from this and support the idea of freedom of expression."

Ulf Johansson, editor in chief of Nerikes Allehanda, said he took the bounty "more seriously" than other threats he had received. "This is more explicit. It's not every day somebody puts a price on your head."

Johansson said he had contacted the police and that they had already started work on the threat.

Aside from a few scattered protests and condemnations by Muslim countries, the reaction to the cartoon has been muted, in contrast to last year's fiery protests that erupted in several Muslim countries after a Danish newspaper published 12 cartoons of Muhammad that were reprinted in a range of Western media.

In an attempt to defuse the tensions caused by the cartoon in both Sweden and abroad, Swedish Prime Minister Fredrik Reinfeldt last week invited 22 Sweden-based ambassadors from Muslim countries to talk about the sketch.