US blames Iran for attacks on Gulf oil tankers

US Secretary of State Mike Pompeo accused Iran of being behind attacks on two oil tankers near the Persian Gulf, and said it was taking the case to the UN Security Council.

Pompeo told reporters in Washington that the attacks were the latest in a series of "provocative actions" that have sharply raised tensions in the region.

"This [assessment] is based on intelligence, the weapons used, the level of expertise need to execute the operation, recent similar Iranian attacks on shipping," Pompeo said.

"Taken as a whole these unprovoked attacks present a clear threat to international peace and security, a blatant assault on the freedom of navigation and an unacceptable campaign of escalating tension by Iran,"

"And the fact that no proxy group operating in the area has the resources and proficiency to act with such a high degree of sophistication," he added.

The US planned to raise the attacks at the UN Security Council later on Thursday.

Pompeo also said the US would defend its forces and interests in the Middle East but gave no details on any immediate plans.

Tensions between Iran and the US have been growing since President Donald Trump last year withdrew from an international agreement aimed at restricting Iran's nuclear programme.

Trump has since re-instated economic sanctions that have had a devastating effect on the Iranian economy.

In May, the US rushed an aircraft carrier strike group and other military assets to the Persian Gulf region in response to what it said were threats from Iran.