Iraqi security officials say insurgent attacks on Shi'ite pilgrims heading to Karbala Tuesday have killed at least 30 people and wounded many more.

In the latest incident, two suicide bomb blasts targeted Shiite pilgrims in Hilla, south of Baghdad, killing at least ten.

Earlier, assailants opened fire and detonated bombs as pilgrims walked toward Karbala, south of Baghdad, ahead of a Shi'ite religious observance later this week. At least 20 people were killed.

In the capital, a bomb blast near a security checkpoint killed at least four Iraqi troops.

U.S. and Iraqi forces are continuing house-to-house searches today in the Shi'ite stronghold of Sadr City, in Baghdad.  The U.S. is also building a security post in the district.

U.S. military official, Major General Joseph Fil Jr., said the first two days of the security sweep in Sadr City are a promising first start and met no resistance.

In other news, the U.S. military says two bomb blasts killed nine American soldiers and wounded four others north of Baghdad on Monday.  The military said the attacks took place in Salah ad Din and Diyala provinces.
Meanwhile, Iraqi Prime Minister Nouri al-Maliki Monday ordered an investigation into a joint Iraqi-British raid on a national intelligence agency, which uncovered prisoners who apparently had been tortured.

Mr. Maliki has called the raid in the southern, Shi'ite-dominated city of Basra illegal and irresponsible.  He did not mention the prisoners.

British officials said Iraqi forces, supported by coalition troops, raided the office on Sunday looking for what they called terrorists.  But the troops found more than 30 prisoners, including a woman and two children, some of whom showed signs of torture. 

Some information for this report was provided by AFP, AP and Reuters.