Media playback is unsupported on your device Media caption David Cameron: ''Contracts that are not fulfilled will have... pretty tough financial consequences''

MPs have urged ministers to "get a grip" on G4S to ensure a smooth Games.

The Commons Public Accounts Committee says the security firm, whose staff shortages have seen an extra 3,500 soldiers drafted in, should be fined.

Chairman Margaret Hodge said shortages were "predictable". The government says it is on track for a great Games.

Labour leader Ed Miliband, meanwhile, is urging a government re-think on outsourcing more police services to private firms in light of the "fiasco".

In a speech, he argued that police budget cuts of 20% in England and Wales by 2015 meant forces were "under pressure to outsource on a scale and at a speed never before seen".

And he said G4S' "ability to deliver" should be reviewed before it is awarded any new policing contracts.

The government says spending reductions will not mean worse services.

In other developments as the UK prepares for the start of the Olympics on Friday 27 July:

The Ministry of Defence denies "ridiculous" suggestions that servicemen and women are being forced to sleep on office chairs following Olympics security shifts after photos emerge on social media sites

Olympic medallist Steve Backley and artist Tracey Emin are among those carrying the Olympic torch as it travels from Deal to Maidstone, in Kent.

Great Britain's women's basketball team are beaten 88-63 by USA despite a spirited performance in a Games preparation match in Manchester

PM David Cameron says a planned strike by thousands of Home Office workers - including airport immigration workers - which could disrupt the Games would not be "right or justified".

Drivers on East Midlands Trains will strike from 6-8 August, union Aslef says, threatening disruption to spectators travelling to the Games

Last week, it emerged the armed forces were on standby to provide an extra 3,500 troops to help with security at the London Games, amid fears that private contractor G4S would not be able to provide enough trained staff in time.

On Tuesday, the firm's chief executive, Nick Buckles, agreed when questioned by the Commons Home Affairs Select Committee that the debacle was a "humiliating shambles for the company".

The company may lose £50m from the £284m contract because it cannot supply enough security guards.

Meanwhile, Metropolitan Police Commissioner Bernard Hogan-Howe has told radio station LBC that people should be "reassured that the policing is in place, the military have come in to fill that gap that G4S have left".

'Post-mortem'

Unveiling her own committee's report, Ms Hodge criticised G4S and the London Organising Committee of the Olympic and Paralympic Games (Locog).

Media playback is unsupported on your device Media caption Margaret Hodge MP says she wants 'true transparency' from G4S

She said: "The chaos which has emerged over the security contract was predictable and undermines confidence in those responsible for managing the Games.

"There is now a last-minute scramble to make sure there will be enough security personnel on the ground."

"In evidence to us before Christmas, all those concerned gave assurances that the contract could be met despite more than doubling the number of guards before the ink was dry on the original contract."

She added: "Now troops are having to be drafted in. The Home Office needs to get a grip on Locog and G4S urgently.

"We still don't know just how many security guards will actually be delivered or whether G4S will face any penalty. We will carry out a post-mortem in September," she said.

She later told BBC News: "The more you get private providers providing public services, the more important transparency becomes because it's your and my money - it's the taxpayers' money - that's being used."

She said there had been a 12-fold hike in management costs, from £10m to £125m, and that G4S had still failed to deliver.

"That seemed to us completely unjustifiable - we want to look at it in detail to make sure that the taxpayer is not being ripped off," she added.

'Safe and secure'

The report states that G4S should not only pay for all additional costs but face financial penalties for the "failure to deliver".

If a company doesn't fulfil its contract, then that company should be got after for that money PM David Cameron

It adds that there has been no overall figure about how much the Games are costing the taxpayer.

There is a public-sector funding package of £9.3bn, but other Games-related expenditure, such as funding of elite athletes, will also come from the public purse.

Prime Minister David Cameron, meanwhile, said G4S could be forced to give back some of the money it has been paid.

"If a company doesn't fulfil its contract, then that company should be got after for that money," he told BBC News during a visit to Afghanistan.

"That's exactly what's going to happen in the case of G4S."

Culture Secretary Jeremy Hunt said the government was "on track to deliver a great Games on time and under-budget".

He said he disagreed that his department had lacked transparency.

Media playback is unsupported on your device Media caption Jeremy Hunt: "Now is not the time for a blame game."

"London 2012 has arguably been more transparent than any other public sector project."

Mr Hunt said the government had worked closely with Locog and G4S on security arrangements and had "moved quickly to activate our contingency plans".

He later told BBC One's Breakfast that overall, with eight days to go until the start of the Games, there had been "a very encouraging start".

"This week, the athletes arrived in the village, people were worried about immigration and queues at Heathrow, that went smoothly, people were worried about the transport network in London and that went pretty well," he added.

Meanwhile, it has been revealed that the organisers of London 2012 encouraged G4S to keep wages for security staff as low as possible.

Security guards have been offered £8.50 an hour to work at the Olympic venues - below the market rate of about £10 an hour.

G4S was "incentivised" in the contract - renegotiated and enhanced in December - to keep a lid on labour costs, meaning higher profits if it paid less.

A spokesman for Locog said: "The combined pay and retention rate starts at over £9 per hour.

"The more senior [the] role, the higher the rate."

G4S was unavailable to comment.