WASHINGTON — Five people and four companies have been indicted on a charge of allegedly plotting to export 6,000 radio control devices to Iran, including 16 of the items that were found in improvised explosive devices in Iraq, the Justice Department announced today.

Authorities in Singapore arrested four people in the case Monday. The fifth defendant is a resident of Iran who remains at large.

According to the indictment, in 2008 and 2009, U.S.-led forces in Iraq recovered numerous radio controls manufactured by a Minnesota firm used in a remote detonation system for IEDs. The radio devices can transmit data wirelessly as far as 40 miles with a powerful antenna.

The defendants allegedly made tens of thousands of dollars for arranging the transportation of the 6,000 radio devices in five shipments from June 2007 to February 2008.

Some of the defendants also are accused of conspiracy involving exports of military antennas to Singapore and Hong Kong.

The defendant who is at large, Hossein Larijani, is a citizen of Iran. The four people arrested are all citizens of Singapore.