Iran says it will free on humanitarian grounds seven of the 23 crew members of a British-flagged oil tanker that it seized in the Strait of Hormuz in July.
The sailors – five Indians, one Latvian and one Russian – have already left the Stena Impero, a foreign ministry spokesman told state television.
Iran has alleged that the vessel broke "international maritime rules".
The seizure came two weeks after an Iranian tanker was held off Gibraltar with the help of the Royal Marines.
That ship, now called the Adrian Darya 1, was suspected of violating European Union sanctions on Syria. But it was released by Gibraltar on 15 August.