Iran's navy seized a foreign vessel in the Gulf and arrested its crew on suspicion of fuel smuggling, state media said Wednesday, in the second such operation in a week.

"A foreign ship, carrying 550,000 litres of smuggled fuel, was seized in the waters of the Persian Gulf," the judiciary chief for Hormozgan province, Mojtaba Ghahremani, told state TV.

"The smuggled fuel was seized and seven crew members arrested," he added, without specifying their nationalities.

"Operational forces and naval vessels of the Islamic republic seized the vessel and escorted it to port," Ghahremani said, adding that "the ship has been handed over to the judicial authorities for legal proceedings and necessary investigations."

Iran's navy has stepped up its operations against fuel smuggling in the sea lanes of the Gulf, where a large portion of the world's oil is produced and shipped.

On Friday, Ghahremani said two vessels were seized and their six crew members detained.

Last month, at least three similar seizures were reported, on April 9, 15 and 24.