British security giant G4S says its failure to provide enough guards for the London Olympics will cost about STG50 million ($A76.65 million) as it struggles to recover from the fiasco.
The company announced in a results statement that it had booked the loss as an exceptional item in the first half. The provision was at the top end of its prior forecast.
G4S added that pre-tax profits slumped 60 per cent to 61 million in the six months to the end of June, hit also by restructuring costs after it slashed 1100 jobs worldwide. Net profits tumbled 74 per cent to STG30 million.
Just two weeks before the Olympic Games began, G4S revealed it could not completely fulfil its STG284 million contract to provide 10,400 security staff for Olympic venues.
It triggered a political firestorm and the British government was forced to deploy an extra 4700 troops to cover the shortfall.
Under-fire chief executive Nick Buckles admitted he was "deeply disappointed" about the problems with the Olympics contract.
"We were deeply disappointed that we had significant issues with the London 2012 Olympics contract and are very grateful to the military and the police for their support in helping us to deliver a safe and secure Games," Buckles said.
"The overall business has performed well in achieving a similar underlying profit as the first half of last year despite economic challenges, particularly in Europe, and weakness in the US government market."
Speaking on a conference call, Buckles added that he needed to prove to investors that he deserved to keep his job.
"I hope I keep my job," he told reporters.
The London-listed firm is carrying out an Olympic contract review which will be completed next month.
G4S meanwhile reassured investors that it would have enough staff to cover the Paralympics, which start in London on Wednesday.
"We continue to work with our partners to ensure that the Games are safe and secure," it said.
"We are confident that we have an assured security workforce for the Paralympic Games and do not anticipate any workforce shortfall issues to arise."