Iranian authorities have arrested 11 foreign nationals on suspicion of attempting to smuggle fuel out of the country, state television reported on Wednesday. The arrests in the country's south come as Iran faces difficulties importing enough fuel to meet demand as the US maintains a naval blockade of Iranian ports. "Border guards arrested 11 foreign suspects," state television reported, without specifying their nationalities. It said the guards acted on intelligence reports of smuggling attempts using a tugboat in Gulf waters. During a search of the boat, the guards "discovered 382,000 liters of diesel fuel", it added. Iranian authorities have for years sought to curb widespread fuel smuggling, particularly in the south along the Gulf, where it has contributed to local shortages. More recently, Washington imposed its blockade of Iranian ports in retaliation for Tehran's closure of the Strait of Hormuz, a vital conduit for Gulf oil and gas shipments, after the Middle East war broke out in February. On Tuesday, parliament speaker Mohammad Bagher Ghalibaf called on citizens to curb petrol consumption. Long queues have formed at filling stations in Tehran in recent days.