G4S, the security contractor, admitted on Wednesday that it would not be able to provide more than 10,000 security staffers by the time the Olympics begin in less than two weeks.

The government hurriedly announced it would bring in 3,500 military personnel to boost security for the Games.

Sports Secretary Jeremy Hunt said Sunday it should be no surprise that some contractors were unable to meet their commitments.

"It's completely normal that you're going to find some contractors on a project of this size who aren't going to be able to deliver what they promised," he said on the BBC's Andrew Marr show.

He praised the contractor as being "honorable" for having admitted the problem, apologizing and covering the costs of bringing in military personnel.

And he reiterated that the government learned only last week that G4S would not meet its commitment.

"Management told us right up until last week that everything was on track," Hunt said.

The contractor said Saturday it stands to lose up to $77 million after failing to recruit enough staff.

Also on Sunday, the Home Office rejected a newspaper report that it had been cautioned about G4S in September of last year.

The Home Office, which is responsible for domestic security, said it was "inaccurate" that a report by the police watchdog agency Her Majesty's Inspectorate of Constabulary "should have raised alarm bells about the readiness of G4S."

The report "into Olympics security preparedness -- which has never been published -- raised serious issues over G4S last year," the Independent on Sunday said.

The Home Office denied that.

"While an early inspection highlighted issues to be addressed, a report in February 2012 said that LOCOG was on track to deliver the required number of security personnel," the Home Office said in a statement. LOGOC is the London Olympic Games Organising Committee, which is running the Games.

G4S chief executive Nick Buckles said Saturday he was "deeply disappointed" the firm was unable to live up to its contract with LOCOG.

"We clearly took in a contract in good faith," Buckles said. "We were a vital part of securing the games. The military would have to be called in to help us through that process. We know a number of these soldiers had had to cancel leave to come back and help us with the process ... we feel we caused a huge problem."

Buckles acknowledged the company was at fault and said it was grateful the military is providing support. "We are sorry they had to give up leave, truly," he said.

"It is down to G4S ... we were contracted to deliver staff. We should have done that."

London Olympics organizer defends security contractor

The military deployment means that 17,000 military personnel will be on duty in the United Kingdom during the Games, compared with the 9,500 currently in Afghanistan.

A Ministry of Defence spokesman said the security operation will not impact operations in Afghanistan, which is the main effort for the military. Some personnel who would have had leave over the Olympic period will have the leave rescheduled, the spokesman said.

G4S had been expected to recruit a staff of about 10,400 as part of a total security force of 23,700 for the Olympic and Paralympic Games.

The staffers were to provide venue perimeter security, including manning X-ray machines, conducting spectator and vehicle searches and operating closed-circuit television, said G4S spokesman Adam Mynott.

The contractor said this week that while 4,000 are already at work across 100 venues, more than 9,000 are still going through the training and vetting process.

In a statement Saturday, the company said it had "encountered significant difficulties in processing applicants in sufficient numbers through the necessary training, vetting and accreditation procedures. As a result, we will be unable to deliver all of the necessary workforce numbers."

UK: 3,500 extra troops called in for Olympic security

That failure is likely to cost the firm between £35m and £50m ($54 million -$77 million), it said.

G4S "deeply regrets that, despite the relentless efforts of so many of its people, it is unlikely to deliver in full its obligations to LOCOG, to the government and to everyone with an interest in these Games."

Britain is on a heightened state of alert ahead of the Games, which open on July 27.

Home Secretary Theresa May said Thursday that "there is no question of Olympic security being compromised."

But opposition lawmakers have described the situation as a "shambles," saying it raises concerns over the government's grip on the preparations for the Olympics and Paralympics.

LOCOG chairman Sebastian Coe said Friday he was "extraordinarily impressed with" private contractor G4S so far.

Coe said he was happy with the security staff on site and that while G4S has "challenges," it would get there.

Olympic organizers have agreed to give 10,000 tickets to the armed forces to compensate for the short-notice deployment, the Ministry of Defence said.

The questions over security staff come as Britain gears up to welcome many of the visiting teams' officials this weekend ahead of the athletes' arrival on Monday.

One headache was removed for organizers with the reopening Friday of the main highway linking Heathrow airport with central London. The busy M4 motorway had been closed for a week for emergency repairs to a viaduct.