PETROL prices are set to soar in the UK after Iran-backed drone strikes on the world's largest oil plant in Saudi Arabia.

Experts claim the attacks are the "equivalent of 9/11" to the global oil industry with the market expected to see an increase of $5(£4) to $10(£8) per barrel when it opens on Monday - with fears prices at the pump across Britain could increase 5p per litre.

Prices could even spike to as high as $100(£80) per barrel if Saudi Arabia fails to quickly resume oil supply lost after attacks over the weekend, it is claimed.

Andrew Lipow, of consultants Lipow Oil Associates, predicted a 5p rise per litre of petrol and added: “This is a big deal.”

Attacks on two plants at the heart of the kingdom's oil industry knocked out more than half of Saudi crude output.

State-run oil giant Saudi Aramco said the strikes would spark a drop in output of 5.7million barrels per day or more than five per cent of global crude supply.

An upped-priced $10(£8) barrel could mean the cost at petrol pumps would rise to between 3 and 4p per litre.

Tilak Doshi from oil and gas consultants Muse, Stancil and Co, said: "In the oil universe, this attack is perhaps equivalent to the 9/11 attacks.

"Abqaiq is easily the world's single most important oil production and processing infrastructure site."

And Iran earlier warned the US it's "ready for a fully-fledged war" and American bases are "within range of our missiles".

The threat, from a top Revolutionary Guards commander, comes hours after the drone attacks.

Iran dismissed accusations by the US that it was behind Saturday's strikes on Saudi oil plants that disrupted world oil production.