"The lifting of the detention order against Stena Impero was finalized today, but the investigation into some of its violations and environmental damage remains open. The owner and captain of the ship have made a written commitment to accept a court's decision in this regard," Mousavi said on Twitter.
On Monday, Iranian government spokesman Ali Rabiei said that Tehran had completed the legal procedures necessary for releasing the tanker. Iranian Ambassador to London Hamid Baeidinejad, on his part, said that Stena Impero was now free to leave Iran.
Stena Impero was seized by the Iranian Islamic Revolutionary Guard Corps in the Strait of Hormuz on 19 July over an alleged violation of international maritime rules. The move came after Iran's Adrian Darya 1 oil tanker had been seized by UK marines off the coast of Gibraltar over an alleged breach of EU sanctions imposed on Syria.
Iran's tanker was released on 19 August after Gibraltar reportedly received assurances that the cargo would not be delivered to Syria.