BAGHDAD, May 15 (UPI) -- A spokesman for the U.S. military in Baghdad said emerging evidence suggests Iran is backing the so-called special groups targeting coalition and Iraqi forces.

"Over the course of the last several months, we have publicly discussed numerous times, and shown numerous times, the evidence on four separate occasions on what we have found and continue to find: Iranian-made weapons in the hands of criminals in Iraq," Army Maj. Gen. Kevin Bergner said at a Baghdad news conference.

Shiite fighters in Iraq "are being trained in Iraq and receiving funding from Iranian Quds Forces to conduct violent attacks in Iraq," Bergner said.

The Quds force is a branch of the Iranian Revolutionary Guard. Its top commander, Brig. Gen. Qassem Soleimani, played a role in the cease-fire negotiations regarding the April conflicts in Basra and the May conflicts in Sadr City.

Bergner said U.S. officials would work with a special committee established by Iraqi Prime Minister Nouri al-Maliki to examine claims of Iranian violations of Iraqi sovereignty, including the weapons claims, the American Forces Press Service, the military division of the U.S. Defense Department, said Wednesday.

"I think (the weapons issue) has awakened (Iraq) to the reality of the magnitude of Iranian meddling in Iraq," U.S. Defense Secretary Robert Gates told a panel at the conservative Heritage Foundation Tuesday. "And so we are being very aggressive in going after the networks in Iraq and the individuals who are interfering and are supplying weapons from Iran."

Gates noted that U.S. strategists had "other activities" in progress to deal with the apparent Iranian backing of militants.