Iran’s Revolutionary Guards on Thursday said they have seized a foreign tanker and its crew for allegedly smuggling fuel, AFP reported. “With a capacity of two 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 force said.

The tanker was seized south of the Iranian island of Larak, the force said. However, it did not name the vessel or its place of origin. The tanker had 12 people on board, CNN reported quoting Iran’s Fars news agency.

Iran had initially claimed that it came to the help of the tanker, which had sent out a distress signal. “Iranian forces approached it and using a tugboat brought it into Iranian waters for necessary repairs,” Foreign Ministry Spokesperson Abbas Mousavi said.

Meanwhile, US Central Command chief Kenneth McKenzie pledged to “work aggressively” to protect freedom of navigation in the Persian Gulf. “We are going to work very aggressively with our partners... to come to a solution that will enable the free passage of critical oil and other commodities... through the region,” McKenzie told reporters at an air base in Saudi Arabia.

Tensions between Iran and the United States have steadily increased since last month, when Tehran shot down an American spy drone over the Strait of Hormuz. While Iran claimed the drone had violated its airspace, the US maintained it was shot down over international waters. The incident came days after the United States accused Iran of attacking two of its oil tankers in the Gulf of Oman on June 13.

On July 11, the United Kingdom claimed that three Iranian boats tried to impede a British oil tanker in the Gulf. The incident took place while commercial vessel British Heritage was trying to pass through the Strait of Hormuz.