The crew of the British tanker seized by Iranian forces in the Strait of Hormuz will remain on board to observe safety regulations, a local Iranian official said Saturday.

Iran said Friday it had confiscated British tanker Stena Impero in the strategic waterway, in a move that followed Britain’s July 4 seizure of an Iranian flagged oil tanker off Gibraltar, a British overseas territory that abuts southern Spain.

London said the Iranian tanker was suspected of smuggling oil to Syria, in violation of EU sanctions on the Bashar al-Assad regime.

Iranian authorities said the 30,000-ton British-flagged ship has been taken to Iran for legal procedures.

“There are 18 Indian and five crew members from Russia, Philippines, Latvia and other countries on board of Stena Impero. The captain is Indian, but the tanker is UK-flagged,” Allahmorad Afifipour, director general of Ports and Maritime Affairs of Hormuzgan province, said in statements cited by the official IRNA news agency.

“Stena Impero crashed into a fishing vessel,” he said, adding that the captain of the vessel had tried to make contact with the UK tanker, but there was no signal.

Iran has demanded the release of its crew and vessel and has threatened London of retaliatory measures, a rhetoric that is raising tensions between the two nations in a region already inflamed with war and brinkmanship with the west.