According to the border force, the suspicious items were found upon inspection in the freight set to be flown off from the airport.
"We had a couple of O rings that we identified. O rings are pieces of rubber that go between tubes to stop leakage to seal them. They can be used in oil, but they can also be used for warheads and the like. Our staff stopped them from going to Iran," Monique Wrench, the UK Border Force’s deputy director at Heathrow, told the Evening Standard.
According to Wrench, the equipment looked like it was intended for an oil refinery.
"But the dots don't quite join up here," the official said, adding that the investigation was launched into the issue.
Any transactions on selling missile-related equipment or technology to Iran are prohibited under UN Security Council resolution 1737 adopted in 2006 over proliferation risks of Iran's nuclear program. The Joint Comprehensive Plan of Action, also known as the Iran nuclear deal, which presupposes lifting of some anti-Iranian trade restrictions, does not nullify sanctions related to the missile production.