Iraq's prime minister toured the northern city of Tall Afar near the Syrian border on Monday to congratulate Iraqi forces for ousting militants from their stronghold, Iraqi television reported.

In Baghdad, meanwhile, a huge car bomb exploded outside a popular restaurant in the upscale Mansour neighborhood, witnesses said. Hospital officials said at least two people were killed and 17 were wounded. A doctor at Yarmouk Hospital said most of the victims were women.

Al-Iraqiya television, which showed no pictures of Prime Minister Ibrahim Jafari's visit to the Tall Afar area, said he was there despite an insurgent threat to unleash chemical and biological weapons against Iraqi and U.S. forces.

There was no known public threat from the insurgents to use unconventional weapons in the area, but they have vowed in two Web postings since Friday to use chemical weapons against U.S. and Iraqi government interests in Baghdad. The threats mentioned the fortified Green Zone that houses the U.S. Embassy, Iraq's parliament and other government offices.

On Sunday, Abu Musab Zarqawi, leader of al Qaeda in Iraq, posted audio on the Internet accusing U.S. and Iraqi forces of using poison gas in the Tall Afar offensive. The authenticity of the statement could not be independently verified, but the voice was similar to the one used in other postings attributed to Zarqawi.

U.S. officials consistently have denied using poison gas in warfare.

In the northern city of Kirkuk, gunmen shot and killed two policemen, police Col. Adil Zain Alabideen said. And in Hujjaj, north of Tikrit, Iraqi police found the bodies of four Iraqi soldiers, said Sameer Sumaidae, a physician at a local hospital. The four had been handcuffed and shot, he said.

The U.S. Embassy annex in the southern city of Basra was hit by a "multiple rocket attack" early Monday, an American official in Baghdad said. The official said there were no injuries or deaths, and no significant damage. He declined to discuss the damage or where the rockets hit, other than to say they landed "in the vicinity" of the compounds.

Special correspondent Salih Saif Aldin in Tikrit contributed to this report.

Prime Minister Ibrahim Jafari praised Iraqi forces in the northern city.