One worker who reported for 2012 Games duty in Glasgow after travelling from Northern Ireland was sent home because there were no uniforms left, MPs found.
It was among a series of failures by the controversial security firm, the world's largest, uncovered by the House of Commons Home Affairs Committee.
The report released today calls for G4S to return the £57 million handling fee it received for the Games. The Herald revealed earlier this week the firm had failed to pay many of the staff they recruited for the Olympics and Paralympics.
MPs are also demanding the firm make generous payments to staff who underwent training and accreditation and were never called up for work.
Many were left out of pocket by the company's failure to assign them shifts, it warns.
In addition, MPs called for the Government to create a register of high-risk companies who have failed to deliver on major public-sector projects.
Committee chairman Keith Vaz said he did not think firms should be barred from Government contracts if their names appeared on the list. But he said it was important when dealing with procurement contracts worth billions that there was a log of companies who had failed to come good on their promises.
There was outrage in the run-up to the Olympics when the Coalition Government was forced to call in the Army to help with security .
G4S had been commissioned to provide more than 10,000 security guards but just two weeks before the opening ceremony it admitted it was thousands short of its target.
In Glasgow, the Army and Strathclyde Police stepped in to take control of security at Hampden, where a number of football matches were being played.
The report found those who signed up to work for G4S were assigned shifts in different parts of the UK, with no offer of accommodation. It added: "One applicant from Northern Ireland says he reported for work in Glasgow as requested but was sent home because G4S had run out of uniforms."
The report said the blame for the debacle lay firmly and solely with G4S, which estimates it has lost £50m because of the shambles.
MPs also called on the company to give up its £57m management fee, describing it as only a fraction of the £759m the company receives from the British taxpayer every year.
They said: "Parliament and the general public would regard it as absurd for the company to be claiming a management fee which was clearly negotiated on the basis of the delivery of services which were not delivered.
"We recommend the Government establishes a register of high-risk providers, who have a track-record of failure in the delivery of public services. We expect the company to make public a means by which people can be recompensed in such circumstances and to be quick and generous in settling such claims."
Mr Vaz added: "The taxpayer must not pay for G4S's mistakes. G4S should waive its £57m management fee."
In a statement, G4S said it noted the Commons report, adding: "The Board and management of G4S have taken responsibility for the inability of the company to deliver, in full, on the Olympic security contract and apologise for this failure."
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