Iraq's foreign minister says four Iraqi military officers have been detained in the kidnapping this week of an Iranian diplomat.

Hoshyar Zebari (file photo)

Foreign minister Hoshyar Zebari told reporters in Baghdad Wednesday that the four men, although military officers, were apparently not linked to the government. He did not elaborate.

He said the men are being questioned about who ordered the kidnapping.

Gunmen in Iraqi army uniforms kidnapped the Iranian diplomat on Sunday.

Iran has said it holds the United States responsible for the safety of the diplomat. An Iranian spokesman said the kidnappers are linked to Iraq's defense ministry, which, he said, "works under the supervision of American forces."

The U.S. has denied involvement in the incident.

U.S. forces in Iraq arrested a number of Iranians recently.

Washington has accused Tehran of aiding Shi'ite militants involved in sectarian attacks.

Some information for this report was provided by AFP and Reuters.