The government squandered almost £500m by leasing RAF transport aircraft that it could have bought outright for less money.

The Ministry of Defence wanted to buy the four Boeing C17 Globemasters for £520m but was told by Gordon Brown, then the chancellor, to lease them because it would be cheaper.

New figures show the MoD paid a total of £769m to lease the aircraft and then had to buy them anyway for an additional £220m. The final payment was made last month, putting the total price over eight years at £989m.

The MoD’s financial problems are now so great that the prime minister has still not signed off on its spending plans for this financial year.

The giant C17 transporters, flown by 99 Squadron based at RAF Brize Norton in Oxfordshire, can carry three Warrior armoured vehicles or a dozen Land Rovers. The MoD has since bought two more for £130m each, putting the total for the RAF’s six-aircraft fleet up to £1.25 billion.

Gerald Howarth, the Conservative defence spokesman, said the lease deal had been “an absolute shocking waste of public money when our troops are going without the equipment they need”.

The MoD said the decision to lease the aircraft was taken to meet a short-term need. Buying the leased aircraft to cope with operations in Iraq and Afghanistan was subsequently seen as “the best value-for-money option”.

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