Iran’s Revolutionary Guard has seized an oil tanker carrying 700,000 litres of “smuggled fuel” in the Persian Gulf, according to the country's media.
State TV and the semi-official Fars news agency said seven crew members were detained when the ship was seized late on Wednesday.
They did not provide further details on the vessel or the nationality of the crew.
The news agency reported that the ship was seized near Farsi Island, where an Iranian Guard Navy base is located.
The island sits in the Persian Gulf between Saudi Arabia and Iran, north of the Strait of Hormuz.
“This foreign vessel had received the fuel from other ships and was transferring it to Persian Gulf Arab states,” Fars quoted General Ramazan Zirahi, a Guard commander, as saying.
This would mark the third commercial vessel seized by Iranian forces in recent weeks and the second accused of smuggling fuel.
Tensions have soared in the Gulf in recent months as the US has boosted its military presence and oil tankers have been seized by Iranian forces or targeted by unknown saboteurs.
The tensions are rooted in the US decision last year to withdraw from the 2015 nuclear accord and impose sweeping sanctions on Iran.
Iran recently began openly breaching limits set by the nuclear agreement, saying it cannot abide by the deal unless European signatories provide some kind of economic relief.
In July, Iran seized a British-flagged vessel in the Gulf in what some Iranian officials suggested was retaliation for the seizure of an Iranian oil tanker in a British Royal Navy operation off Gibraltar.
The UK said the Iranian oil tanker was suspected of violating European Union sanctions on oil shipments to Syria.
Meanwhile, Iran said a fighter jet has gone down in the south of the country near the Persian Gulf, with two pilots surviving the crash.
The state-run IRNA news agency quoted a local official as saying the crash was caused by a technical problem.
Abdolhossein Rafipour, the governor of Tangestan, said the plane went down near the coastal town at 1230 local time (0800 GMT).
The purpose of Sunday’s flight was not immediately clear. Regular patrol flights are common in the region.
Iran’s air force has an assortment of US-made military aircraft purchased before the 1979 Islamic Revolution.
It also has Russian-made MiG and Sukhoi planes.
Decades of Western sanctions have made it hard to maintain the ageing fleet.