Petrol prices will increase up to 18¢ a litre at some sites today - the biggest single-day jump in almost two years.
Though the average metropolitan price will be 144.8¢ a litre across the city, most BP sites will raise their unleaded petrol price 18¢ a litre to 149.9¢.
Most Caltex and Caltex Woolworths sites will raise their prices 16¢ to 147.9¢ a litre.
FuelWatch spokesman Kyle Huynh said although the average metropolitan price had dropped about 5 per cent in the past five weeks, prices were expected to rise in the short term, mainly because of security issues in the Middle East. More than 40 Perth sites will sell petrol below 137¢ a litre today.