U.S.-backed Iraqi troops seized a launcher loaded with more than a dozen Iranian-made rockets and detained three suspected militants after an attack against the American base outside the southern city of Basra, officials said Tuesday.

Col. Karim al-Zaidi said the missiles were found in an eastern section of Iraq's second largest city after rockets targeted the U.S. base Monday evening.

The U.S. military confirmed that 16 rockets were found and three suspects detained by Iraqi troops who responded to the attack. It said no casualties were reported.

The oil-rich area of Basra has been a Shiite militia stronghold but violence has declined sharply following a U.S.-Iraqi offensive that led to a cease-fire last year.

Still, attacks continue. Three American soldiers were killed in a rocket attack against the base in mid-July.

American commanders say Iran is continuing to support violence in Iraq. Tehran denies the allegation.

A cease-fire called by anti-U.S. cleric Muqtada al-Sadr after his forces were routed in Basra and Baghdad's Sadr City district has been a key factor in ebbing the rampant sectarian violence that pushed the country to the brink of civil war.

But Shiite extremist factions, including a group known as Asaib Ahl al-Haq or League of the Righteous, broke with al-Sadr, raising fears that the bloodshed could resume.

The Shiite-led government announced earlier this month that it has entered into talks with Asaib al-Haq and the group promised to renounce violence and lay down its weapons.

In return, the government promised to work to free detainees linked to the group, which has been accused of involvement in the killing of five American soldiers in a bold raid south of Baghdad and the kidnapping of five British men two years ago.

Salam al-Maliki, a spokesman for the group, said the government has agreed to release all 300-400 detained members in exchange for a truce that includes ending attacks against U.S. forces.

"About 100 members have been released so far and we are committed to stick to our promises and to support the political process in Iraq as long as the government continues to honor its promises and the foreign forces continue to withdraw," he told The Associated Press on Tuesday.

Gen. Ray Odierno, the top U.S. commander in Iraq, said the group's members appeared to be respecting the cease-fire and have begun to turn in heavy weapons or at least to consolidate the heavy weapons that they have."

Several high-profile Shiite detainees have been released from American custody this summer, including key Asaib al-Haq member Laith al-Khazali in June. He and his still-detained brother, Qais, were accused of organizing a daring attack on a local government headquarters in Karbala that killed five U.S. soldiers on Jan. 20, 2007.

Ali al-Lami, who headed a commission responsible for keeping Saddam Hussein loyalists out of government posts but was accused of ties to Shiite militias and detained in August 2008, also was freed last week, officials said.

The U.S. command at the time accused al-Lami of being involved in the bombing of a municipal building in Sadr City that killed eight people, including two American soldiers and two State Department employees.

The U.S. military has been freeing inmates or transferring them to Iraqi custody as part of a security pact that took effect on Jan. 1.

Odierno told reporters Monday that practice would continue, even if those released have been linked to attacks that killed Americans.

He insisted that anybody with "blood on their hands" will be tried in Iraqi courts but conceded that the evidence against many suspects was insufficient for prosecution even if the military had strong reason to believe they were guilty.

"This is about reconciliation," he said. "We believe Asaib al-Haq has taken initial steps to reconcile with the government of Iraq."