Iranian state television said Thursday forces from the country's Revolutionary Guard seized a foreign tanker accused of smuggling oil.
The report said the vessel was intercepted Sunday in a section of the Strait of Hormuz south of Iran's Larak Island with 12 crew members on board.
It said the tanker was involved in smuggling one million liters of fuel, but did not give details about its country of origin.
The seizure comes after the Panamanian-flagged tanker MT Riah, which is based in the United Arab Emirates, disappeared from ship tracking maps in Iranian territorial waters on July 14.
The Revolutionary Guard said it received a distress call from the vessel, which was "later seized with the order from the court as we found out that it was smuggling fuel," a report said. It said Iranian smugglers intended to transport the fuel to foreign customers.
"The United States strongly condemns the Islamic Revolutionary Guard Corps Navy’s continued harassment of vessels and interference with safe passage in and around the Strait of Hormuz," a State Department spokesperson said. "Iran must cease this illicit activity and release the reportedly seized crew and vessel immediately."
The seizure comes amid heightened U.S.-Iran tensions, which began to escalate when President Donald Trump withdrew the U.S. from a 2015 deal with Iran and world powers last year and imposed stiff sanctions on Iran, including on its oil exports.
Iran has recently exceeded uranium production and enrichment limits in violation of the agreement in an effort to pressure Europe to offer more favorable terms to allow it to sell its crude oil abroad.
The U.S. has also deployed thousands of additional troops, nuclear-capable bombers and fighter jets to the Middle East.
Veiled attacks on oil tankers and Iran's downing of a U.S. military surveillance drone have further fueled concerns of a military conflict in the Persian Gulf region.
An unnamed U.S. defense official told Associated Press earlier this week the U.S. "has suspicions" Iran seized the tanker MT Riah when it turned off its tracker.