Speaking to AFP in Baghdad, Stoltenberg's comments were his first on the strikes on two major Saudi oil facilities, which were claimed by Yemen's Huthi rebels but which both Washington and Riyadh have blamed on Tehran.

"We call on all parties to prevent any such attacks occurring again because that can have negative consequences for the whole region, and we are also extremely concerned about a risk of escalation," the secretary general said.

Stoltenberg, who said the alliance "strongly condemned" the attacks because of the destabilising effect on oil supplies, also had a message for Iraq's neighbour, Iran.

"We are concerned about what we see, especially from Iran. Iran is supporting different terrorist groups and being responsible for destabilising the whole region," he charged.

The strikes on Abqaiq -- the world's largest oil processing facility -- and the Khurais oil field in eastern Saudi Arabia have roiled global energy markets and sent prices spiking.

Huthi rebels said they carried out the attacks with 10 drones, but American media have reported that US officials had satellite images showing the attacks -- possibly with drones and cruise missiles -- had come from the north or northwest, rather than Yemen.

The Saudi-led coalition on Monday said its preliminary probe had found Huthi rebels were not responsible, while squarely pointing the finger at Iran for providing the weapons used in the attacks.

It said it was still investigating where the strikes had originated.

Iraq, home to several Iran-backed paramilitary factions, has been placed in an awkward situation amid rising tensions between its two main allies, Iran and the US.

Baghdad has denied the attacks were launched from its country, with Prime Minister Adel Abdel Mahdi reiterating Iraq's aim to stay neutral in a call with US Secretary of State Mike Pompeo on Monday.

According to the premier's office, Pompeo told Abdel Mahdi that the US had also found that Iraqi territory was not used in the attacks.

The US has declined to comment directly.