An image grab taken from Iran's official Press TV station five Iranians upon their arrival at Tehran, 12 Jul 2009

Five Iranians released from U.S. custody three days ago in Iraq, received a warm welcome Sunday at Tehran's Mehrabad Airport.  The United States insists the five were not released as part of a political gesture to Iran.

The five Iranians released Thursday in Iraq, were given a hero's welcome at Tehran's Mehrabad Airport, as a crowd of well-wishers and family members greeted them on the tarmac.

Iranian Foreign Minister Manouchehr Muttaqi embraced the men, as friends and relatives carried them on their shoulders into the airport.  Muttaqi later gave a press conference, surrounded by the five, complaining that the United States had detained them "illegally."

He also insisted that Iran does not intend to let the matter drop.  "Iran," he said, "reserves the right to legally pursue this savage action by the government of [former U.S. President George W.] Bush."

The U.S. military transferred the five Iranians into Iraqi custody on Thursday, and Iraqi authorities immediately handed them over to the Iranian Embassy in Baghdad.

The men were arrested in Iraq's northern Kurdish capital of Erbil in January of 2007.  The U.S. military says the five belong to the elite Quds forces of Iran's Revolutionary Guards, and accuses them of helping militants attack U.S.-led forces with high-tech explosives.

The Iranian News Network (IRIN) called the detention of the five "illegal and barbaric" and showed footage of alleged damage to the Iranian consulate in Irbil, after the five men were arrested by the U.S. military.

State Department spokesman Ian Kelly said Thursday U.S. forces released the five in response to an order by the Iraqi government to transfer all third country nationals being held in U.S. custody to Iraqi authorities.

Kelly said the United States has concerns about freeing associates of the Iranian Revolutionary Guards, but he said it is obligated to its agreement with the Iraqi government.

Iraqi Foreign Minister Hoshyar Zebari called the release of the five Iranians "a good initiative," saying that it could encourage dialogue between the United States and Iran.

Iran has long contended that the five men were "diplomats" and Foreign Ministry spokesman Hassan Qashqavi recently charged their detention violated international diplomatic agreements.

There had been speculation the five Iranians may have been released as part of a bargain between the United States and Iran for the freedom of detained U.S.-Iranian journalist Roxana Saberi, but State Department spokesman Kelly insisted that was not correct.