Iranian state TV is reporting that the country's Islamic Revolutionary Guards Corps (IRGC) seized a foreign tanker on July 14 with 12 crew members on board.
State TV reported on July 18 that the tanker was transporting fuel from Iranian smugglers to foreign customers and was intercepted south of Iran's Lark Island in the strategic Strait of Hormuz.
The report did not identify the tanker nor the nationalities of the crew members.
"With a capacity of 2 million barrels and 12 foreign crew on board, the vessel was en route to deliver contraband fuel received from Iranian boats to foreign ships in farther regions when it was intercepted," the IRGC's Sepahnews website said.
The website said the vessel the IRGC seized was the same one Iranian forces towed on July 14.
TankerTrackers, a cargo-shipment-tracking service, identified the vessel that was towed by Iran as the MT Riah, a Panamanian-flagged ship owned by the United Arab Emirates.
TankerTrackers said the MT Riah had crossed into Iranian waters on July 14 and that its last known position was off Qeshm Island in the Strait of Hormuz.
Iranian Foreign Ministry spokesman Abbas Musavi said on July 17 that Tehran towed an vessel into an Iranian harbor after it suffered a technical malfunction. He did not identify the ship.
The United States said that the vessel was from the United Arab Emirates and that its crew had not been in contact with its owner since its transponder was turned off on July 13.
A U.S. defense official also told the Associated Press that Washington had "suspicions" that Iran had seized the vessel.
Britain seized an Iranian tanker off the coast of Gibraltar on July 4 over allegations that it was breaking European Union sanctions by attempting to ship oil to Syria.
Iran has called for Britain to release the tanker and has threatened to seize British ships in retaliation.
Tensions have been on the rise between Washington and Tehran after U.S. President Donald Trump last year withdrew from a landmark international deal under which Iran scaled back its nuclear program in exchange for sanctions relief.
Russian President Vladimir Putin and his French counterpart, Emmanuel Macron, agreed on July 18 on the need to "consolidate efforts" to save the 2015 deal, an "important factor in ensuring security in the Middle East," the Kremlin said.
Iran's President Hassan Rohani also urged Europe on July 18 to "accelerate" its efforts to salvage the deal during a phone call with Macron, saying, "Iran is determined to keep open all options" to preserve the agreement, a statement on the government's official website said.
He warned Macron that "missed opportunities" would force Iran to drop further commitments under the deal, after it rescinded some limits on its nuclear activities in May.