A US warship shot down an Iranian drone after it came within 1000 yards and ignored repeated warnings to back off, President Donald Trump has said.

The US president said the drone was shot down at 10am on Thursday local time in the Strait of Hormuz in the Persian Gulf.

Mr Trump said the USS Boxer took "defensive action" after the drone “closed into a very, very near distance, approximately 1,000 yards” and ignored “multiple calls to stand down.”

The drone was “threatening safety of the ship and the ship's crew” and “was immediately destroyed,” he said.

He added: “This is the latest of many provocative and hostile actions against vessels operating in international waters. The United States reserves the right to defend our personnel, our facilities, our interests, and calls upon all nations to condemn Iran's attempts to disrupt freedom of navigation and global commerce."

A Pentagon statement confirmed that a "fixed-wing unmanned aerial system... closed within a threatening range" of the USS Boxer.

"The ship took defensive action against the UAS to ensure the safety of the ship and its crew," it added.

The incident comes amid a period of heightened tension between the two countries, which included Iran last month shooting down a US drone it said was flying over the country.

That incident saw Mr Trump call off a retaliatory strike at the last minute because he said too many people would have died.

The US decision has pulled out of a historic nuclear deal brokered with Iran under President Barack Obama, and imposed strict sanctions on the country.

Iran, meanwhile, has recently increased uranium production.