G4S chief Nick Buckles 'deeply disappointed' by Olympics fiasco as £50m hit forces profits down 60pc

"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," Mr Buckles said.

In its half-year report, G4S also revealed that it has cut 1,100 jobs so far this year in a bid to protect growing margins.

A rise in revenues to £3.9bn in the six months to June 30 from £3.6bn in the same period last year was driven by a better performance in developing markets such as Africa.

Pre-tax profits fell to £61m from £151m in 2011.

Just weeks before the Olympic opening ceremony, G4S admitted it had failed to recruit the full 10,400 staff it had promised under the terms of its contract. The Government was forced to send in thousands of soldiers to make up the shortfall.

G4S has begun an investigation into the failure, which should be completed by the end of September.

Despite the fiasco, Mr Buckles remains confident that his workforce can cope with the Paralympic Games, which starts on Wednesday.

"We are confident that we have an assured security workforce for the Paralympic Games and do not anticipate any workforce shortfall issues to arise," he wrote in the report.

The company will be looking for a successful Paralympics to help draw a line under its problems and build on revenues that grew 8pc in Europe, 4pc in North America and 10pc in developing markets, despite a global slowdown.

The loss of several Government contracts last year has been offset by new business from the Ministry of Justice, UK Border Agency, Lincolnshire Police and Oakwood prison.

"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," Mr Buckles added.

In a bid to buoy growth, G4S has cut more than 1,100 jobs in the first six months of the year. Costs related to this restructuring hit £24m, with a further £10m still to come. G4S hopes the move will generate savings of £30m a year.

G4S kept its interim dividend on hold at 3.42p per share.

The shares fell 1.65pc to 261.8p in early trading.