South Africa's government ignored the advice of its air force chiefs and bought 24 Hawk jets from BAE Systems, Britain's biggest defence company, costing twice as much as a competing aircraft from Italy, it emerged yesterday.

An official investigation into a bitterly controversial arms deal disclosed that the £1.5 billion contract awarded to BAE Systems and its partner, the Swedish aerospace company Saab, included the supply of 28 Gripen jet fighters that the South African air force did not want.

The final report on the deal, released by the auditor general and prosecuting authorities in 2001, did not mention these matters. They came to light only when earlier drafts of their report were disclosed to yesterday's Business Day, a South African newspaper, prompting accusations of an official cover-up.

A passage from the draft report, excised before publication of the final report, said: "There were fundamental flaws in the selection of BAE-Saab as the preferred bidder."

The investigators found that BAE Systems was favoured by Joe Modise, the late defence minister.

Mr Modise overruled his air force chiefs, who according to the draft report wanted their new jet trainer to be the Italian Aermacchi MB339, not the Hawk, which cost twice as much.

The draft report includes the recommendations of a committee of officials from the defence and finance ministries, and the state arms company. They concluded there was no military rationale for buying the Gripen fighters. Instead, the government went ahead with the order and the first Gripens are due for delivery in 2007.

The total cost of the deal, including contracts awarded to other suppliers, has now risen to more than £4.4 billion. The courts compelled the government to hand over the draft reports after legal action from a failed bidder.

A BAE Systems spokesman said: "These [matters] have been looked at over and over again. These findings have not been accepted by the South African government and we must refer you to the South African government. They are the people who make the decision. We also can't comment on the pricing from the competition."

The auditor general's office issued a statement declining to comment on draft versions of the report, explaining that they were provisional and subject to change *, and standing by the findings of the final published report into the deal.

With acknowledgements to David Blair and the Telegraph.

*       Previously, as spouted forth so many times in Parliament, before SCOPA, in official public press releases and in sworn affidavits, these findings were final and not subject to change whatsoever.

Only an independent judge can, without doubt, finally proclaim on this matter.