LONDON - The British government has put extra soldiers on standby to provide security for the London Olympics following concerns the private contractor G4S would not train enough guards in time for this month's Games.

Some 23,700 security guards will protect the Olympic venues as part of Britain's biggest peacetime security operation, and 13,500 military personnel have already been earmarked to contribute to this.

However, fears over whether G4S would recruit enough guards in time has prompted the government to take action with the Olympics due to start on July 27.

"We have agreed to offer help to G4S by revising the level of military support," a spokeswoman for the Home Office said.

Media reports said 3,500 soldiers had been put on standby but the spokeswoman said exact details would be confirmed by the Defence Secretary on Thursday.

Chester, a Metropolitan Police explosives sniffer dog searches Victoria Coach Station in the run up to the London 2012 Olympic Games in London, July 12, 2012. [Photo/Agencies]

The security guards will provide airport-style checks to search and screen spectators, and can also check vehicles, such as buses, travelling through the Olympic Park in east London.  

They will also be responsible for queue management and protecting the perimeters and equipment.  

More than 100,000 people applied for the 10,400 temporary jobs in what G4S had described as one of the biggest paid recruitment drives in Britain this century.

Last week, Ian Horseman Sewell, managing director of G4S Global Events, told Reuters in an interview that the company was "absolutely on track to deliver".

"This has been an unprecedented and very complex security recruitment, training and deployment exercise which has been carried out to a tight timescale," a G4S spokesman said.

"We have encountered some issues in relation to workforce supply and scheduling over the last couple of weeks, but are resolving these every day and remain committed to providing a security workforce for the start of the London 2012 Games."

Mayor of London, Boris Johnson, removes his jacket as he passes through a security check during his visit to the 2012 Olympic Park in London, July 12, 2012. [Photo/Agencies]

In December, the government and London Olympic organizing committee (LOCOG), the body responsible for staging the Games, were forced to double the number of guards from 10,000 after they admitted underestimating the number needed.

It meant the deal with G4S to provide security at the venues, rose from 86 million pounds ($135.15 million) to 284 million pounds.

That led to widespread criticism from lawmakers and Tessa Jowell, the opposition Labor Party's Olympic spokeswoman, said there needed to be answers why the latest issues had arisen so close to the Games.

"This is clearly a serious problem, and we have to understand how this problem arose," she said.  

LOCOG said it did not envisage any increase in the overall number of venue guards would be required.

"Security for the Games is big and complex but we have the best brains in the security business working on this - Home Office, Metropolitan Police, MoD (Ministry of Defence) and world's largest private security business," a LOCOG spokesman said.

Soldiers man a security checkpoint at an entrance to the London 2012 Olympic Park at Stratford in London July 12, 2012. Britain's interior minister had to answer questions in parliament on Thursday after admitting that she was putting extra troops on standby for Olympic security, just two weeks before the London Games begin, because a private contractor might not meet its commitments. [Photo/Agencies]