BAGHDAD - U.S. and Iraqi troops moved against al-Qaeda in Iraq on two fronts yesterday, with house-to-house searches in Mosul and an operation in the desert to stanch the flow of insurgents and weapons to that northern city.

With the new sweep, Prime Minister Nouri al-Maliki is aiming to put down Sunni extremists after launching two other major offensives elsewhere in the last two months targeting Shiite militants. Mosul, a key transport crossroads between Baghdad, Syria and other points, is considered the last major urban base of al-Qaeda in Iraq after the group lost strongholds in western Anbar province.

U.S.-backed Iraqi troops searched homes and the U.S. military announced that the forces in Mosul captured a suspected al-Qaeda figure involved in organizing car bombings and smuggling foreign fighters into the country. There were no reported clashes during the searches in the western and eastern parts of Mosul, Iraq's third-largest city, where insurgents are believed to use the cover of sheep and produce markets to smuggle cash, weapons and foreign fighters from nearby Syria.

Sheikh Fawaz Jarba, a leader of Sunni tribes in Mosul opposed to al-Qaeda, complained that the sweep was "unorganized" and that public warnings of the coming raids enabled al-Qaeda fighters to flee.

U.S. Marines were operating farther south, near Lake Tharthar, a remote desert region that has been a refuge for al-Qaeda and a back channel for supplying the network in the north. "We're trying to shut down the rat lines," said Marine Brig. Gen. Richard Mills.

Marines yesterday searched an abandoned mud house, uncovering six weapons caches including material for building roadside bombs.

Marine Capt. Josh Biggers said they discovered evidence that insurgents had recently used the area: broken eggshells scattered across a floor in one room, new electrical fixtures, and the outline on the floor of what troops believe may have been a generator.

Lake Tharthar - once Saddam Hussein's favorite fishing spot - lies between Mosul and the former Sunni insurgent strongholds of Fallujah and Ramadi. Many al-Qaeda fighters hid in the desolate region after losing control of those cities, and the U.S. military believes the group has been using it for training and as a supply route.

U.S. troops discovered nearly 200 bodies in mass graves in that region late last year and early this year. This week, troops discovered two more bodies in the area - proof, the military says, that al-Qaeda is still trying to operate in the area.

Since the Marines began their operation five weeks ago, they have killed six Sunni insurgents in clashes, Brig. Gen. Randolph Alles said.

In Mosul, about 225 miles northwest of Baghdad, Maliki met with former Hussein-era army officers and tribal chiefs to seek their backing for the new crackdown.

Maliki is calling on authorities to facilitate the return of those who wish to resume military duty. He promised that the security sweep would be followed by money to build infrastructure in the city and employ its residents.

Deadly Raids in Afghanistan

Foreign intelligence

agents are leading secret, deadly raids on suspected insurgents in Afghanistan and shirking responsibility when civilians are killed,

a U.N. official alleged.

Philip Alston,

a special investigator on the U.N. Human Rights Council, yesterday noted three such recent raids in the country's south and east.

He did not mention

specific agencies but appeared to imply U.S. involvement. U.S. military officials declined comment.

Alston said

the raids were part of a wider problem of unlawful killings of civilians and lack of accountability in Afghanistan. He said about 500 civilians were killed this year, most by the Taliban but some by Afghan police.

The allegations

came as

a suicide bomber wearing a burqa attacked a police patrol in Farah in western Afghanistan, killing five police officers and seven civilians. The Taliban claimed responsibility.

- Associated Press