An image from the Islamic Republic of Iran News Network on Sunday reportedly shows a foreign tanker seized by Iran in the Persian Gulf. (IRINN/AFP/Getty Images)

Iran said it has seized another foreign vessel suspected of smuggling fuel in the Persian Gulf, state media reported Sunday, adding to growing tensions over a spate of incidents involving oil tankers in the region.

The naval forces of the Islamic Revolutionary Guard Corps detained the ship and seven crew members in a “surprise operation” authorized by Iran’s judiciary, the organization said in a statement. The seizure comes amid Iranian efforts to “detect and fight against organized smuggling,” the statement continued.

The Revolutionary Guard did not identify the ship or give the nationalities of its crew members but said that the vessel, which it said was Iraqi, was carrying roughly 185,000 gallons of smuggled diesel fuel.

It was the third ship seized by the Revolutionary Guard in recent weeks amid a simmering standoff between Iran and the West in the Persian Gulf.

The energy-rich region has become a flash point for the wider conflict between Iran and the United States over the Trump administration’s campaign to isolate Tehran. The United States, which has withdrawn from a 2015 nuclear deal Iran struck with world powers, has imposed harsh sanctions on the Iranian economy and says it wants to reduce Iran’s oil exports to “zero.”

A Revolutionary Guard commander, Gen. Ramazan Zirahi, told reporters Sunday that the vessel was seized near Farsi Island, where his forces maintain a naval base, in Iranian territorial waters in the gulf, state television reported.

He said the raid on the ship was carried out Wednesday night following an intelligence-gathering operation that established the vessel’s involvement in smuggling fuel to Arab nations in the gulf.

Those states are also major energy exporters. But Iran’s cheaper fuel, subsidized by the government, could be sold to foreign buyers for a higher price on the black market, analysts said. Smuggling operations have increased as a result of U.S. sanctions.

Industry analysts say tankers carrying Iranian crude have masked their locations to defy U.S. restrictions and forged documents to conceal the origin of Iranian cargo. 

Last month, authorities in Gibraltar seized an Iranian tanker carrying 2.1 million barrels of light crude oil, cargo they suspected was on its way to the Syrian refinery at Baniyas. Officials in the British territory said the vessel was seized to enforce compliance with European Union sanctions, which prohibit the sale of oil to Syria.

Iran says it is not subject to E.U. sanctions and has called the ship’s detention an “act of piracy.”

Revolutionary Guard commandos last month captured the British-flagged Stena Impero near the Strait of Hormuz, which connects the Persian Gulf with the Gulf of Oman and is a key waterway for global oil shipments.

Iran said the tanker had violated international maritime law. But the seizure followed an earlier attempt by Iran to block the British Heritage tanker from traversing the strait, the British government said. A Royal navy frigate, the HMS Montrose, repelled the Iranian vessels that approached the tanker.

The United States has urged its allies to contribute to a maritime security initiative in the Persian Gulf to secure global oil shipments, many of which link Arab energy producers with energy markets in Asia.

Also last month, Iran detained the Panama-flagged Riah, which it said was involved in fuel-smuggling operations.

The incidents follow a string of attacks on petrochemical tankers in and around the Strait of Hormuz since May, acts of sabotage that the United States blamed on Iran. Iranian officials have denied involvement.