Motorists can expect a hike in the price of petrol and diesel prices within weeks following attacks on two Saudi oil processing plants, according to AA Roadwatch.

The warning came as the cost of a barrel of oil surged after drone strikes on national energy giant Aramco's Abqaiq processing plant and Khurais oil field at the weekend.

The attack has knocked 5.7 million barrels per day off production, more than half of the OPEC kingpin's output.

The increase in the price of a barrel may not mean anything right now but it could have a significant impact on consumers of home heating oils as well as motorists, according to the AA Roadwatch's director of consumer affairs Conor Faughnan.

Mr Faughnan said that while it was hard to say how much of an increase we might see because of the other factors at play, prices at the pump could increase by as much as 6 to 8 cent per litre.

Speaking to RTÉ News Mr Faughnan said unless oil prices drop, Irish consumers will start to see an increase in the cost of petrol and diesel in around four to five weeks time.

Mr Faughnan said: "We’ll find out over the next week or so whether the oil price is going to stay at it’s current high level. We simply don’t know - that depends on market movement.

"But if it does then you will be looking at a significant price increase being evident at Irish pumps in around about four to five weeks time from now. That’s the normal length of the supply chain."

Mr Faughnan said there are a number of other factors that complicate matters such as the exchange rate between the euro and the US dollar as well as the price of refined product being bought in Europe.

Crude oil is a naturally occurring type of fossil fuel which is extracted and refined and used for petrol, diesel and home heating products.

All of which we use a lot of in Ireland, according to Mr Faughnan. Therefore, he said, when prices increase there is not much we do to avoid them.

Today's 20% increase in Brent crude oil is the biggest gain since the 1991 Gulf War.

Additional reporting AFP