An attack on a major oil facility in Saudi Arabia means that a predicted drop in the petrol price for October will be lower than anticipated, according to the Automobile Association (AA). 

The AA was on Wednesday commenting on unaudited mid-month fuel price data released by the Central Energy Fund.

"The refinery strike was a game-changer for the way oil price stability is viewed. At a single stroke, five to seven percent of the world's oil output was wiped from the board, leading oil prices to surge disproportionately," the AA said in a statement. 

The association said it now expects the price of a litre of 95 octane petrol to drop by 5 cents, and a litre of 93 octane by 20 cents in October. On Friday, before the attack cut Saudi oil production by half, CEF data was indicating a drop of 11 cents for 95 octane and 25 cents for 93 octane petrol. 

It expects the price of diesel to increase by 13 cents a litre. 

The AA added that more changes were likely before month-end, saying the drone strikes had made forecasting the international oil price more difficult.