FUEL prices are likely to rise by as much as 20c a litre early next month following recent rises in world oil prices. Figures from the Central Energy Fund show a price underrecovery of some 17c per litre. If oil prices remain at their current levels, the petrol price will have to be raised by the same amount. A rise of between 15c and 20c per litre willrepresent the biggest single rise this year, and will take fuel prices to their highest level ever.