BAGHDAD - Iran is using the Lebanese Shiite militia Hezbollah as a "proxy" to arm Shiite militants in Iraq and Tehran's Quds force had prior knowledge of a January attack in Karbala in which five Americans died, a U.S. general said Monday.

U.S. military spokesman Brig. Gen. Kevin J. Bergner said a senior Lebanese Hezbollah operative, Ali Mussa Dakdouk, was captured March 20 in southern Iraq. Bergner said Dakdouk served for 24 years in Hezbollah and was "working in Iraq as a surrogate for the Iranian Quds force."

The general also said that Dakdouk was a liaison between the Iranians and a breakaway Shiite group led by Qais al-Kazaali, a former spokesman for cleric Muqtada al-Sadr. Bergner said al-Kazaali's group carried out the January attack against a provincial government building in Karbala and that the Iranians assisted in preparations.

Al-Khazaali and his brother Ali al-Khazaali, both captured in March, have told U.S. interrogators that they "could not have conducted it (the Karbala attack) without support from the Quds force," Bergner said.

Documents captured with al-Khazaali showed that the Quds Force had developed detailed information on the U.S. position at the government building, including "shift changes and defense" and shared this information with the attackers, the general said.

U.S. officials at the time of the Karbala attack said it was unusually sophisticated, with the attackers dressed in U.S. uniforms to get close to the building, and suggested Iran may have had a role in it...