Iran is demanding the release of its oil tanker seized by Britain, saying the move sets a dangerous precedent and must end now.
British Royal Marines impounded the tanker in Gibraltar last week, on suspicion it was carrying oil to Syria, in violation of European Union sanctions.
But in a twitter post, Foreign Minister, Mohammad Zarif, accused Britain of carrying out an unlawful seizure, calling the act piracy.
Iran denies the vessel was headed to Syria, where the government of President Bashar al-Assad is an ally of Tehran.
