Iranian naval vessels have repeatedly made “dangerous and harassing” approaches to US ships in the Persian Gulf near Kuwait, the US military said.

US Naval Forces Central Command in Bahrain said in a written statement that 11 vessels of the Iranian Revolutionary Guard Corps maneuvered near the US vessels while they were operating with US Army Apache attack helicopters in international waters.

The Iranian boats repeatedly crossed the bows and sterns of the US ships at close range and high speeds, the statement said, adding that in one case an Iranian vessel came within 10 yards of a US vessel.

Iranian officials did not immediately acknowledge the incident.

United States Iran Navy
A fifth of the world’s oil passes through the Strait of Hormuz (US Navy/AP)

Tense incidents remain common between Tehran and Washington’s forces in the Persian Gulf and its narrow mouth called the Strait of Hormuz, through which a fifth of the world’s oil passes.

Iran seized ships last summer and Washington has accused it of attacking tankers in the region amid tensions over US President Donald Trump unilaterally withdrawing America from Tehran’s nuclear deal with world powers.

On Tuesday, armed men boarded and briefly held the Hong Kong-flagged tanker SC Taipei and its Chinese crew before releasing the vessel.

The US-led International Maritime Security Construct, a group created to deter Iranian attacks in the region, acknowledged the incident in a statement late on Wednesday and it “assessed no immediate threat to the free flow of shipping in the area”.