"Iran is neither a member of the EU nor subject to any European oil embargo. Last I checked, EU was against extraterritoriality. UK's unlawful seizure of a tanker with Iranian oil on behalf of #B_Team is piracy, pure and simple. It sets a dangerous precedent and must end now," Zarif said on Twitter.
On Thursday, the Gibraltar government said it had detained an Iranian tanker carrying oil to Syria as it had "reasonable grounds" to believe the vessel was acting in breach of EU sanctions against Syria.
Acting Spanish Foreign Minister Josep Borrell reportedly said later that day the vessel was detained per the request of the United States.