The US believes the attack on Saudi Arabia’s oil sites came from southwest Iran but its allies are not convinced as Iran continues to deny it was responsible.

The United States believes the attack on Saudi Arabia’s oil facilities originated in southwestern Iran, a US official told Reuters.

Three officials, speaking on condition of anonymity, said the attack involved both cruise missiles and drones, indicating the attack involved a higher degree of complexity and sophistication than initially thought.

The officials did not provide evidence or explain what US intelligence they were using to make the assessments.

However, such US intelligence, if it could be shared publicly, could increase pressure on the US, Saudi Arabia and others to respond.

One of the three officials expressed confidence that Saudi Arabia’s collection of materials following the attacks would yield “compelling forensic evidence … that will point to where this attack came from”.

A US team is helping Saudi Arabia evaluate evidence from the attack, which was claimed by Houthi rebels in Yemen who are battling a Saudi-led coalition.

Iran denies any role in the attack on the world’s biggest crude oil processing plant, which knocked out half of Saudi Arabia’s oil production.

In a sign that US allies remain unconvinced, French Foreign Minister Jean-Yves Le Drian said he was unsure if anyone had any evidence to say whether drones “came from one place or another”.

Relations between the US and Iran have deteriorated since President Donald Trump pulled out of the Iran nuclear accord last year and reimposed sanctions on its oil exports.

For months, Iranian officials issued veiled threats, saying that if Tehran were blocked from exporting oil, other countries would not be able to do so either.

However, Iran has denied any role in a series of attacks in recent months, including bombings of tankers in the Gulf and strikes claimed by the Houthis.

Vice President Mike Pence said the US was reviewing evidence that suggests Iran was behind the attackss and stands ready to defend its interests and allies in the Middle East.

“We’re evaluating all the evidence. We’re consulting with our allies. And the president will determine the best course of action in the days ahead,” Pence said.

Iran’s foreign minister said in a tweet on Tuesday the US was in denial for suspecting Iran over the attacks and ignoring that Yemenis were fighting back after years of war against the kingdom.

“US is in denial if it thinks that Yemeni victims of 4.5 yrs of the worst war crimes wouldn’t do all to strike back. Perhaps it’s embarrassed that $100s of blns of its arms didn’t intercept Yemeni fire,” Mohammad Javad Zarif said on Twitter.

“But blaming Iran won’t change that.”

Meanwhile, President Donald Trump said on Tuesday he is not looking to meet Iranian President Hassan Rouhani during a United Nations event at the end of the month.

“I’m not looking to meet him. I don’t think they’re ready yet but they’ll be ready,” Trump said.

“I never rule anything out but I’d prefer not meeting him.”

Rouhani said on Monday he would not meet Trump at the UN General Assembly in New York.

– AAP