Saudi Arabia has warned that if it finds that last week’s attack on its oil facilities were launched from Iranian territory then it would be considered an “act of war”.

“We hold Iran responsible because the missiles and the drones that were fired at Saudi Arabia ... were Iranian-built and Iranian-delivered,” minister of state for foreign affairs Adel al-Jubeir told CNN late on Saturday.

“But to launch an attack from your territory, if that is the case, puts us in a different category... this would be considered an act of war.

“The Iranians have to know that there will be consequences to their actions.”

The 14 September attacks on the Abqaiq and Khurais facilities were the largest-ever assault on the kingdom’s oil facilities and initially halved Saudi’s oil production, which accounts for almost 6 per cent of global output.

Attack on major oil facilities in Saudi Arabia: In pictures Show all 10 1 /10 Attack on major oil facilities in Saudi Arabia: In pictures Attack on major oil facilities in Saudi Arabia: In pictures Smoke billows from multiple fires at the Aramco oil processing facility in Abqaiq, Saudi Arabia on 14 September Reuters Attack on major oil facilities in Saudi Arabia: In pictures Thick black smoke billows from a fire following drone strikes on major oil facilities in Abqaiq, Saudi Arabia Planet Labs Inc/Reuters Attack on major oil facilities in Saudi Arabia: In pictures The Aramco oil processing facility in Abqaiq, Saudi Arabia prior to the drone strikes on 14 September AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil processing facility in Abqaiq, Saudi Arabia following drone strikes on 14 September, the previous day (Image 1 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil field in Abqaiq, Saudi Arabia following drone strikes on 14 September, the previous day (Image 2 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil field in Khurais, Saudi Arabia following drone strikes on 14 September, the previous day (Image 1 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Damage is seen to the Aramco oil field in Khurais, Saudi Arabia following drone strikes on 14 September, the previous day (Image 2 of 2) AP Attack on major oil facilities in Saudi Arabia: In pictures Smoke billows from multiple fires following drone strikes on major oil facilities in Abqaiq, Saudi Arabia AFP/Getty Attack on major oil facilities in Saudi Arabia: In pictures Smoke rises from a fire following a drone strike at the Aramco facility in Abqaiq, Saudi Arabia on 14 September Reuters Attack on major oil facilities in Saudi Arabia: In pictures Smoke is seen following a fire at the Aramco oil processing facility in Abqaiq, Saudi Arabia on 14 September Reuters

The attacks were claimed by the Iran-backed Houthi rebels fighting the Saudi-led coalition in Yemen, but doubts have been raised as to whether they have the capabilities to launch such a devastating attack on the kingdom, with Saudi Arabia and its allies in the west pointing the finger at Tehran.

The US has said it has evidence that the attacks were launched from the south of Iran and has since announced plans to send troops to Saudi Arabia and impose new sanctions on Tehran.

US defence secretary Mark Esper told reporters the deployment would be “defensive in nature”.

“The president has approved the deployment of US forces, which will be defensive in nature and primarily focused on air and missile defence,” he said.

Mr Esper declined to give specific numbers but said the deployment would not reach thousands of troops.

In response to the deployment of US troops, Iranian president Hassan Rouhani warned foreign forces to stay out of the Gulf and accused them of threatening the security of the region.

He said they had always brought "pain and misery" and should not be used in an "arms race".

British foreign secretary Dominic Raab said that it was “entirely implausible and lacking credibility to suggest [the 14 September attack] came from the Houthi rebels”, but stopped short of placing the blame on Iran.

He added that the UK was now “looking carefully at all the information” to ensure the UK response is “as robust and widely supported as possible”, he told the BBC’s Andrew Marr.

Riyadh held a press conference this week displaying debris from drones and cruise missiles that they claimed proved Iran’s involvement.

The country has now launched an investigation into the attacks and invited the participation of international observers.

“If they continue along this path, then they risk the possibility of military action,” Mr al-Jubeir said of Tehran.

“But nobody wants war. Everybody wants to resolve this peacefully and the end result has to be an end to Iran’s aggressive policies.”

Iran has denied it carried out the attack with President Rouhani calling it a reciprocal act by the “Yemeni people”.

“US is in denial if it thinks that Yemeni victims of 4.5yrs of the worst war crimes wouldn’t do all to strike back,” foreign minister Javad Zarif wrote on Twitter on Tuesday.

But on Saturday, the commander of Iran’s Revolutionary Guard (IRGC) took a more defiant tone and said the country would “destroy” any aggressor.

“Be careful,” Major General Hossein Salami said on state television.

“Our readiness to respond to any aggression is definitive. We will never allow a war to enter our land. We will pursue any aggressor. We will continue until the full destruction of any aggressor.”

Iran’s deputy foreign minister Abbas Araghchi told The Independent that Iran will “resist militarily” if Washington now seeks to apply military pressure on Tehran.

On Friday, the Saudi-led coalition carried out an attack in Yemen in areas north of Yemen’s port city of Hodeidah, in the first such response since the 14 September strikes.

The Houthis have since said that they would cease missile and drone attacks on Saudi Arabia, warning that it could lead to more “dangerous development”.

Investigation finds evidence of Saudi double-tap strikes in Yemen

The United Nations welcomed the announcement, saying the move “in good faith could send a powerful message of the will to end the war”.

This comes as the United Nations General Assembly convenes in New York this week, where Iran’s president has said he will present a plan for creating security in the Gulf.

“This year we will present a plan to the world at the United Nations that the Islamic Republic of Iran in cooperation with the countries of the region can create security for the Persian Gulf and the Oman Sea with the help of the countries of the region,” Mr Rouhani was cited as saying on his official website. He did not provide further details.

There had been discussions about whether this would provide a forum for a meeting between Mr Trump and Mr Rouhani after the US president appeared to allude to his openness to meet.

But both sides have since stepped back from the possibility, with Mr Araghchi reiterating to The Independent that “Iran will not negotiate under pressure”.

Referring to the crippling US sanctions on the country, he said: “To get real negotiations started, this economic war has to end.”