The AA has called on the Government and the European Commission to investigate soaring diesel prices.
A survey has found that both petrol and diesel prices continued to rise over the last month, with diesel rising at what the AA called a phenomenal rate.
A survey by the Automobile Assocation found that the average price of diesel is 132.4c, a 7.8c increase in the last month, while petrol costs 124.9c on average, which is an increase of 3.8c.
The price of diesel usually drops as summer approaches, but this year's increases have bucked the trend.
Public affairs manager Conor Faughnan says the AA has never seen diesel prices rise so fast or reach so high.
He says the increases are bad news for the consumer's pocket and the Irish economy as a whole.
Mr Faughnan said prices are having a major impact on diesel motorists and also on the cost of haulage and the costs for many businesses.
But the current high prices are not restricted to Ireland, diesel prices are at record highs across Europe and beyond.
Mr Faughnan says the rising oil prices are pushing up the cost of fuel, but there is still no satisfactory explanation for the rise in diesel prices.
