A top U.S. military official told a press conference in Baghdad today that the information comes from a senior Hizballah operative captured in southern Iraq in March.
Brigadier General Kevin Bergner said the senior Hizballah operative, Ali Musa Duqduq, was captured on March 20.
The United States has long accused Iran of helping fund, train, and arm Shi'ite militant groups in Iraq. Iran's government has always denied any links to attacks on coalition soldiers in Iraq.
He said Duqduq served for 24 years in Hizballah and was working in Iraq as a "surrogate" Iran's Islamic Revolution Guards Corps' Quds Force.
He also said the Quds Force and Hizballah were cooperating to bring Iraqis to Iran for special combat training.
"Quds Force, along with Hizballah instructors, train approximately 20 to 60 Iraqis at a time, sending them back to Iraq, organized into these special groups," Bergner said. "They were being taught how to use EFPs [explosively formed penetrators], mortars, rockets, as well as intelligence, sniper, and kidnapping operations."
Bergner said Duqduq was a contact point between the Quds Force and a breakaway militant Shi'ite group. He said that group had been led by Qays al-Khaz'ali, a former spokesman for radical Shi'ite cleric Moqtada al-Sadr.
Al-Khaz'ali and his brother were captured at the same time as Duqduq, according to Bergner.
The U.S. military officer said that al-Khaz'ali's group carried out an attack on a provincial government compound in Karbala in January that killed five U.S. soldiers.
Bergner said that the attackers "could not have conducted this complex operation without the support and direction of the Quds Force."
In the assault on the compound, gunmen posed as a U.S. security team to get past guards.
Hizballah officials have made no comment on the charges.
The United States has long accused Iran of helping fund, train, and arm Shi'ite militant groups in Iraq that are both fighting coalition forces and waging a sectarian battle with armed Sunni groups.
Iran's government has always denied any links to attacks on coalition soldiers in Iraq.