Five Iranian men held by U.S. forces in Iraq since 2007 returned to Tehran's Mehrabad Airport Sunday, authorities said.

The men, who said they were diplomats, were released Thursday after the U.S. military handed responsibility for them to the government of Iraqi Prime Minister Nouri al-Maliki, Iran's state-run Press TV reported Sunday.

The men had been detained in January 2007 in Irbil in the northern Kurdish region of Iraq.

The U.S. military had accused, but never charged, the men with providing money, weapons, bomb technology and guerilla training to insurgents in Iraq, CNN reported Sunday. The men were suspected members of Iran's Islamic Revolutionary Guard Corps Quds Force, U.S. military officials told CNN.

Last month, the Iraqi government freed Laith al-Khazali, an Iranian-linked militiaman detained in the March 2007 killing of five U.S. soldiers in Karbala.