BAGHDAD, Iraq — Iraqi and U.S. troops sweeping through the northern city of Tal Afar yesterday killed 15 suspected rebels and discovered a bomb factory during the second day of a high-profile counterinsurgency offensive.

About 5,000 Iraqi and 3,500 U.S. soldiers rummaging through the bombed-out mountain city found booby-trapped buildings, underground tunnels and large weapons caches but encountered little fighting during two days of operations. Residents estimated that 90 percent of the city of 200,000 had fled, many to a crowded tent camp.

As with similar offensives in other cities and towns this year, most of the rebels appear to have fled into the countryside before U.S. and Iraqi forces entered.

The joint operation has received heavy coverage on state-controlled Iraqi television. For two days, Al Iraqiya network has shown frequent footage from the scene of Iraqi soldiers kicking in doors as they hunt for rebels in the bombed-out city, which had been the site of insurgent attacks on U.S. and Iraqi forces. In Baghdad, Iraqi officials have given regular updates on the fighting and announced plans to push into other cities along the border with Syria, including Sinjar, Rabiaa, Qaim and Akashat.

The offensive drew reproof from some government critics who charged that such operations served more to exacerbate tensions in the city with a mixed Shiite and Sunni population and divert attention from the government's failings to rebuild the country than to defeat the insurgency.

"What is going on there is nothing but a sectarian purge within an official cover," said Adnan al-Duleimi, a Sunni Arab leader. "This kind of policy would bring nothing but more bloodshed, more chaos, and more destruction to Iraq."

But in a televised news conference yesterday, Defense Minister Saadoun al-Duleimi praised the offensive and the conduct of Iraqi troops.

"What is happening in Tal Afar is an example of what should happen in other troubled places of Iraq," said al-Duleimi, a descendant of the same large Iraqi tribe as Adnan al-Duleimi. "The Tal Afar operation is a quality operation by all measures."

The government's upbeat assessments were reflected in the footage on state-controlled television. Iraqis often criticize the nascent armed forces for firing their weapons wildly into the air. But last night, Al Iraqiya showed Iraqi soldiers in desert camouflage uniforms alertly marching through deserted Tal Afar neighborhoods and calmly guarding a group of about 20 bound, blindfolded and seated suspected insurgents.

Tal Afar residents at the camp outside the city described dire conditions, with more than 550 families crowded into 500 tents set up by overburdened relief workers. They described demolished homes and charged that children were killed in the fighting.

"The American forces and Iraqi soldiers ordered us to leave our houses," said Khudair Yas, 50, a Tal Afar resident living in the camp. "We left without extra clothes or food to a camp which has become like a prison."

Los Angeles Times reporters Suhail Ahmed, Shamil Aziz and a correspondent contributed to this report.