Ministry of Defence officials and senior military figures have spent almost £1 billion on taxpayer-funded charge cards over the last four years.
The department spent £986,041,110 on Government Procurement Cards (GPCs), with an average transaction of £240, according to the Daily Telegraph.
No breakdown of the spending has been published but it is believed the bill includes spending on travel and hotels.
The MoD defended the use of the cards, which are aimed at small office expenditure, insisting they provided good value for money.
The figures emerged in a list published by the Cabinet Office of the 20 departments and public bodies which spent the most on the cards.
The Environment Agency and BBC were identified to be among the biggest spenders, with £215,465,490 and £47,932,348 respectively.
There were 14,271 procurement cards within the MoD last December, according to the figures.
An MoD spokeswoman said: "The MoD is one of the largest departments in Government with military and civilian personnel based all over the world.
"This means that we need the speed and flexibility in procurement that the GPC provides.
"The GPC also cuts overhead costs - the NAO (National Audit Office) concluded that a transaction through GPC is on average £28 cheaper than a manual order and payment process - and so provides good value for money for the taxpayer."
The GPC, a Visa card provided to the public sector through six banks, is designed for purchasing "low value, low risk items" up to £5,000, but may be used for spending above this limit.
Cardholders must satisfy themselves that their chosen suppliers provide best value for money.