The helicopters were handed over at the King Abdullah II Air Base in northeast Jordan.

They were the last batch of 12 Black Hawks delivered to Jordan since March 2017.

An American embassy statement said the aircraft "will strengthen the Jordan Armed Forces (JAF), its Quick Reaction Force and Jordan's security".

"The United States is committed to supporting the JAF's efforts to protect Jordan's borders, counter-terrorism, assist in civil defence operations, and defeat ISIS through the international coalition," it said, using an acronym for the Islamic State group.

Jordan is a key recipient of American financial aid and a partner in the US-led coalition battling the jihadists in neighbouring Syria and Iraq.

"The United States and the Hashemite Kingdom of Jordan have a historic and enduring relationship, built on shared values and shared interests," said US embassy charge d'affaires Henry Wooster.

"Our military partnership epitomises our mutual goals for a secure and stable region.

"Today's ceremony marks the beginning of a new JAF capability in the form of a state-of-the-art UH-60 Black Hawk fleet."

Wooster attended the ceremony with US Central Command chief General Joseph Votel and King Abdullah's brother, Prince Faisal bin Hussein.

Black Hawks overflew the base while the Jordanian armed forces conducted a live fire and infiltration demonstration.

Last year, the United States allocated $470 million to Jordan's army and air force, the American embassy said.

This included pilot and maintenance training, spares, ground equipment, weapons, ammunition and shelters for the Black Hawks, it added.

Three years ago, Washington said it would increase overall US assistance to Jordan from $660 million to $1 billion annually for between 2015 and 2017.

Planning Minister Imad al-Fakhoury said in December that US economic aid to Jordan in 2017 was around $812 million.