The price of diesel at the pumps has reached record levels, the AA said today.

The average price is now 143.05p a litre - climbing past the previous high of 143.04p a litre reached on May 5 last year.

The pump price of diesel fell back to 137.59p in July 2011 before starting to climb again. Two years ago, diesel in the UK averaged 113.62p a litre.

The AA said that for a commercial van with an 80-litre fuel tank, the cost of filling up has risen from £90.90 in February 2010 to £114.44 now, having dropped to £110.07 in July this year.

Over the same period, the average price of petrol was 112.03p a litre two years ago and set a new record of 137.43p on May 5, 2011.

Since then, it fell to 132.25p a litre at the beginning of January 2012, before starting the climb to the latest average of 135.39p.

AA president Edmund King said today: "A stronger pound has staved off this moment for longer than might have been expected, but diesel drivers across the country will have been watching in trepidation.

"They hoped that below-record prices would hold until the spring, when winter price pressures on diesel traditionally ease."

He went on: "However, the impact of record diesel prices will be felt by everyone as higher transport costs are passed on to business and consumers. With some delivery and haulage firms adding a diesel surcharge to invoices, costs will rise faster than most people expect and stoke inflation again.

"Like petrol, there is no price transparency in the wholesale and retail diesel market. Although the diesel price has been influenced by refinery closures, unreliable supply into Europe and stock market speculators taking advantage of a tight market, there is no way for businesses and consumers to find out whether or not they are paying a fair price."

Mr King said it was "galling to see Brent crude shoot up from around 112 dollars a barrel earlier this month to nearly 120 dollars now, despite the International Energy Agency's lower forecasts for oil consumption in 2012".

The AA has written to Chancellor George Osborne calling for an investigation of the oil, refining, fuel product and retail markets "to ensure UK families and business are protected from over-inflated prices and supply difficulties".

It has also called for an end to annual fuel duty hikes while the economy falters. This includes cancelling the planned rise in August.

RAC spokesman John Franklin said: "The new record price of diesel shows the issue of rising fuel prices isn't going away. Drivers continue to be hit hard in their pockets during these tough economic times.

"With a further 3p-a-litre fuel duty rise planned in August, we hope the Chancellor will take a look at this in the Budget.

"Rather than plan further increases, he needs to look at how he can help Britain's hard-pressed motorists who are struggling to pay for essential car journeys."