The police in Gibraltar, a British Overseas Territory on the Spanish coast, on Thursday said that it had arrested the master and chief officer - believed to be Indian nationals - of an Iranian oil supertanker seized by its officers last week.
Both men were aboard Grace 1, which is accused of violating European Union sanctions on Syria.
"As part of the ongoing investigation which led to the detention of the VCCL Grace 1 last week, the master and chief officer of the said vessel have been arrested today [Thursday] in relation to breaches of European Union Regulations 36/2012 concerning restrictive measures in view of the situation in Syria," a Royal Gibraltar Police statement said.
"This follows a protracted search of the vessel where documents and electronic devices have been seized and examined," it noted.
Both men are not yet charged and are currently being interviewed "under caution" at the Royal Gibraltar Police headquarters at New Mole House.
"Both have been accorded their legal entitlements and access to consular representation. The investigation is still ongoing and the Grace 1 continues detained under the provisions of the Sanctions Regulations 2019 which are born out of the Sanctions Act 2019," the police statement added.
On July 4, authorities had said there was reason to believe Grace 1 was carrying Iranian crude oil to the Baniyas Refinery in Syria in breach of EU sanctions. Gibraltar port and law enforcement agencies had detained the supertanker and its cargo with the help of Britain's Royal Marines.
Earlier on Thursday, the UK's Ministry of Defence (MoD) said that Iranian boats tried to impede a British oil tanker near the Gulf – before being driven off by a Royal Navy ship. HMS Montrose, a British frigate shadowing the BP-owned tanker, was forced to move between the three boats and the tanker, an MoD spokesperson said.
The Iranian actions in the latest incident have been described by the UK "contrary to international law".
The latest incident comes after Iranian President Hassan Rouhani had warned Britain of "consequences" over the seizure of the country's supertanker last week.