Iran said on Thursday it had seized a foreign tanker smuggling fuel in the Gulf, and the U.S. military commander in the region said the United States would work “aggressively” to ensure free passage of vessels through the vital waterway.

The United States blames Iran for a series of attacks on shipping in the world’s most important oil artery since mid-May, accusations Tehran rejects but which have raised fears the long-time foes could stumble into war.

It was unclear if the impounded ship was the same vessel Iran towed to safety on Sunday after sending a distress signal. Iranian state television had earlier said it was the same ship but the Revolutionary Guards statement did not confirm that.

The Guards said the impounded ship was smuggling one million liters of fuel in the area of Larak Island in the Gulf and had 12 foreign crew.

Oil prices rose after news of the seizure amid rising tensions between Tehran and the West over the safety of shipping in the Strait of Hormuz, a vital gateway for energy exports.

Read more HERE