Mahmoud Seif and Shahrzad Mir Gholikhan were arrested in Vienna after a meeting, in which they took possession of a US helmet-mounted Generation III military night vision system that they intended to illegally export to Iran, the officials said.

The Department of Homeland Security did not specify when the arrests took place or where the Iranians are now, but it said the suspects had arrived in Vienna to pick up their first shipment on November 30.

"Sophisticated night vision systems allow US troops to 'own the night,' giving them a key advantage over their opponents during night-time combat," Assistant Homeland Security Secretary Michael Garcia said in a statement.

"In the wrong hands, these night vision systems pose a threat to our troops around the world."

The arrests capped a more than two-year investigation that began with a tip received by US officials in Florida that a Tehran-based individual was attempting to purchase night vision systems in the United States.

The individual was seeking to buy up to 3,000 night vision units for use by military infantry. Arrangements were eventually made to acquire the equipment through Austria.

Garcia thanked Austrian authorities for their cooperation.