Price monitor Catalist said that an average cost for a litre of unleaded fuel is 90.2 pence, and slightly less than 94 pence for diesel oil.
Last week, the AA said that the price of unleaded petrol in certain areas of the UK had broken the pound per litre mark, and cautioned that there was little chance prices will fall.
The AA also calculates that Britain's drivers are paying £7.5 million more on fuel per day than they were back in January.
However, motorists should be in line for some good news at some time in the future, says AA price analyst Ruth Bridger.
"We don't expect average UK prices to exceed a pound a litre for a long time," he said.