"The kingdom denounces and condemns the Iranian violations of Iraqi sovereignty," said a statement carried by the official SPA news agency following Wednesday's retaliatory strikes by Riyadh's arch-foe Iran.

The Saudi condemnation was the first by an Arab neighbour of Iraq.

The Iranian missiles targeted two Iraqi bases, including the sprawling Ain al-Asad, which houses American and other foreign troops deployed in a US-led coalition fighting the remnants of the Islamic State jihadist group.

The attack has been denounced by the Iraqi prime minister, the foreign ministry and Iraqi President Barham Saleh as a violation of the country's sovereignty.

Saleh also said he rejected attempts to turn Iraq into a "battlefield for warring sides".

In a letter to the UN following the missile attack, Iran said it fully respects the sovereignty of its neighbour Iraq.

On Thursday Saudi Arabia called anew on all parties to observe restraint and avoid an escalation "in order to preserve the stability of Iraq and the region".

Saudi Foreign Minister Prince Faisal bin Farhan on Monday warned of a "very dangerous" escalation following last week's killing of top Iranian commander Qasem Soleimani in a US drone strike in Baghdad.

Saudi Arabia and the United Arab Emirates, both allies of Washington, are vulnerable to Iranian counter strikes.

A string of attacks on Gulf oil tankers last year that were blamed on Iran, and which Tehran has denied, has raised tensions.

Strikes against Saudi oil installations in September also led Riyadh and Abu Dhabi to adopt a more conciliatory approach aimed at avoiding confrontation with Tehran.