"We've made it a priority to pay the debt that we do owe Iran and we have been seeking ways to pay it," Truss told Sky News.
She added that there was a British team in Iran, according to Reuters.
International Military Services (IMS), a subsidiary of the British Ministry of Defense, signed contracts in 1971 to sell more than 1,750 Chieftain tanks and armored vehicles to Iran.
The deals were canceled after the Shah was deposed in the 1979 Islamic Revolution, but Iran had already paid for the undelivered tanks and demanded its money back.
International arbitration in 2008 ruled the UK owed the debt, but it has not yet paid up.
MP/PR