Iran’s military has again seized a tanker that it says was smuggling fuel for “some Arab countries.” It is the third seizure in recent weeks.

The tanker was carrying 700,000 liters of fuel as Local media report that the Iraqi vessel has been taken to Bushehr port. While Iraq’s oil ministry said on Sunday it has no connection with the vessel, Reuters reports that it may be owned by a private Iraqi company.

Tensions between Iran and the U.K. have risen after the U.K.-flagged Stena Impero and her 23 crewmen were detained on July 19. The vessel and crew were taken to the port of Bandar Abbas after making what Iranian forces claimed was an unsafe maneuver.

The Panama-flagged tanker Riah was seized by Iran’s military on July 15. Islamic Revolutionary Guard Corps (IRGC) intercepted the Riah after the tanker made a distress call near Iran’s Larak Island in the Strait of Hormuz. After boarding, the IRGC determined that she was engaged in fuel smuggling. Iran has since released nine Indian crew members from the vessel. Three others remain in detention.

On July 28, The Royal Navy’s HMS Duncan arrived in the Gulf to support the safe passage of British-flagged ships through the Strait of Hormuz. The Type 45 Destroyer will work with Type 23 Frigate HMS Montrose until she comes off duty in late August, ensuring the continuous availability of ships to accompany merchant vessels.

Defence Secretary Ben Wallace said at the time: “Freedom of navigation in the Strait of Hormuz is vital not just to the U.K. but also our international partners and allies. Merchant ships must be free to travel lawfully and trade safely, anywhere in the world,” he said. “While we continue to push for a diplomatic resolution that will make this possible again without military accompaniment, the Royal Navy will continue to provide a safeguard for U.K. vessels until this is the reality.”

Iran has some of the world’s cheapest fuel prices due to heavy state subsidies and the fall of its currency, but the nation has suffered rampant fuel smuggling to Arab countries.

The Strait of Hormuz, one of the world’s most strategically important choke points, is about 90 nautical miles long, with a width varying from about 52 nautical miles to 21 nautical miles. Around a third of the world’s LNG and about 20 percent of the world’s oil passes through the Strait.