A failure in G4S' internal computer systems was the primary reason it is not able to provide a sufficient number of security staff to support the London 2012 Olympic Games this summer.
According to the Independent, the company's IT systems failed to correctly calculate staff rostering, which has now been identified as the "root cause of the problem".
G4S won the security contract with LOCOG, the organisers of the Olympic Games, after it submitted a tender at least 25 percent lower than any of its competitors. However, it was revealed last week that it was not going to be able to fulfil its contractual commitments and the Home Office is being forced to deploy some 3,500 soldiers to cover the shortfall.
Home secretary Theresa May is now under pressure to explain why the government has had to make the decision to deploy troops at this late stage, considering that the Games start in the capital next week.
A statement from May said: "We were receiving reassurances from G4S until very recently, and the absolute gap in numbers was crystallised finally only yesterday [14 July]."
Nick Buckles, chief executive at G4S, has said that the firm faces a penalty of up to Â£20 million for failing to deliver on its Â£284 million contract, as well as having to pay the Ministry of Defence (MoD) Â£30 million for providing the troops, bringing the total cost to Â£50 million.
Computerworld UK contacted G4S to get a statement on the IT failure but had not heard back at the time of publication.