Washington said an Iranian surface-to-air missile has shot down a US military drone in international airspace over the Strait of Hormuz, BBC reported on Thursday.

The drone was identified by the IRGC as a RQ-4 Global Hawk, but a US military official told Reuters news agency that the drone was a US Navy MQ-4C Triton.

The statement came after Iran’s Revolutionary Guard earlier on the same day said it had shot down a US “spy drone” deemed to violate Iranian airspace.

The Iranian military did not immediately publish images of the drone.

The incident comes at a time of growing antagonism between Iran and the US following two waves of still unexplained attacks on Gulf shipping.

The US has accused Iran of being behind the attacks.

Tehran has denied any involvement and hinted that Washington might have orchestrated them itself to provide a pretext for the use of force against Iran.

Tensions have been running high between Iran and the US ever since US President Donald Trump abandoned a landmark 2015 nuclear agreement in May last year.

The subsequent reimposition of crippling unilateral sanctions has dealt a heavy blow to Iran’s already flagging economy.

Washington has also bolstered its military presence in the Middle East in a campaign of “maximum pressure” against Tehran.

Its deployment to the Gulf of an aircraft carrier task force as well as B-52 bombers, an amphibious assault ship and a missile defence battery has sparked fears of fresh conflict in the region.

One of the two tankers attacked in the Gulf of Oman last week was damaged by a limpet mine, the US military said on Wednesday.

On May 12, two Saudi oil tankers and two other ships were damaged in mysterious “sabotage attacks” in the Gulf of Oman off the United Arab Emirates.

Defence Minister Amir Hatami flatly rejected allegations Iran was behind the twin attacks.

“Accusations levelled against Iran’s armed forces and the published film with regards to the incident [that] happened to the vessels … are unsubstantiated and we categorically reject these accusations,” the official news agency IRNA quoted him as saying.