The United States has announced the deployment of 200 troops as well as Patriot missiles to Saudi Arabia to help the country's defence in the wake of last week's attacks on oil installations blamed on Iran.

The Department of Defense said the deployment would involve one battery of the surface-to-air missiles, along with four Sentinel radars used for air and missile defence systems.

In addition, two more Patriot batteries and one THAAD ballistic missile interception system are being readied in case a decision is made to also supply them to the Saudis, Pentagon spokesman Jonathan Hoffman said.

"This deployment will augment the kingdom's air and missile defense of critical military and civilian infrastructure," he said.

It comes "in light of recent attacks on the Kingdom of Saudi Arabia," he added.

Mr Hoffman said: "It is important to note these steps are a demonstration of our commitment to regional partners, and the security and stability in the Middle East.

"Other countries have called out Iranian misadventures in the region, and we look for them to contribute assets in an international effort to reinforce Saudi Arabia's defence."

The US has pointed to Iran being behind the drone and cruise missile attacks on 14 September which heavily damaged two Saudi oil installations, forcing the key oil supplier to slash output.

Iran has denied responsibility, and President Hassan Rouhani has challenged the US and others to provide evidence to back up their accusations.