Kiwi motorists have been rushing to fill up their tanks on Monday over fears of an imminent price rise.

Drone attacks on two major oil facilities in Saudi Arabia have taken out more than five percent of the world's daily supply.

It's lead to fears that pain at the petrol pump could continue after the price of oil surged to its highest level in four months today.

Within seconds of trading opening, crude oil jumped almost US$12 a barrel - the biggest surge on record - before settling down to $8.

"If that stabilised at that level, within the next couple of days we'd be expecting to see an eight cent per litre price increase," energy consultant Ian Twomey says.

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The attack cut the output of the Saudi facilities by 5.7 million barrels of oil per day, and it could take weeks before repairs are completed.

New Zealand only takes between five and ten percent of its supply from Saudi Arabia and experts say that although the damage is extensive, we won't be running out any time soon.

"Stocks are quite high at the moment. The world's got plenty of oil," Twomey says.

The impact is clearly being felt politically though. The attacks have sparked an international row. Yemen's Houthi rebels have claimed responsibility, but the US is pointing the finger at their backers, Iran.

President Trump tweeted on Monday (NZ time) that he believed the US knew who the culprit was and that they were "locked and loaded" and ready to respond if the Saudis suspicions aligned with theirs.

Saudi Arabia has not yet blamed any party for the strike and is expected to tap into its oil reserves so exports can continue this week. Iran has denied involvement, but says it's "ready for a fully-fledged war".

Back here, fuel companies are watching closely before making any changes at the pump. 

"Until we really see what happens in those international markets in the next day or so, it's hard to really understand what the true impact will be for our customers," says Z Energy CEO Mike Bennetts.

But any changes will only be in one direction and the message for motorists is to fill up sooner rather than later.