MPs have spent nearly half a million pounds of public money on business class flights in the last three years, an investigation has revealed.

The number of business class tickets booked by parliamentarians has almost doubled in a single year, with 10 MPs claiming for more than 100 premium air fares each.

The Daily Telegraph reports that 55 MPs have used a loophole in rules that oblige lawmakers to buy economy class tickets to purchase business class flights that can cost as much as £850.

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They found that the practice has cost the taxpayer almost £500,000 since the 2010 general election despite the stricter guidelines being introduced in the wake of the 2009 expenses scandal.

The findings have prompted criticism of Parliament’s reformed expenses system from campaigners, who described the purchase of business and club class tickets by MPs as “outrageous”.

Records kept by expenses watchdog IPSA show that Eric Joyce has been reimbursed for more business class flights than any other MP.

The Falkirk representative, who is serving a 12-month community order for committing assault in a House of Commons bar, has made claims for 208 business-class flights worth £43,410 since May 2010.

Jim Murphy, the shadow defence secretary, has claimed for 188 premium flights at a cost of £33,224, the paper reports.

The loophole permits MPs to be reimbursed for premium air fares so long as the cost is not more than a standard ticket, an IPSA spokesman confirmed.

As a result, some MPs have booked a business class ticket far enough in advance of departure for it to be less expensive than an economy fare booked later.

Matthew Sinclair, chief executive of the Taxpayers’ Alliance, told the paper: “It is outrageous that a number of MPs are still racking up huge bills living the high life at our expense.

“There is absolutely no justification for MPs travelling business class, especially when their own constituents are making the same journeys every day in economy. When our politicians should be looking for ways of saving money and cutting costs, it beggars belief that they feel it appropriate to waste taxpayers’ cash on business class flights.”