More than 6,000 off-duty British troops look set to bolster security at London's Olympic venues next summer, a source said on Friday, as planning continues for what could be the country's biggest security challenge since World War Two.
Organisers are actively looking at possibly using the army during the Games after a reassessment of the numbers needed.
The London organising committee (LOCOG) had appointed the private security firm G4S to recruit, train and manage 10,000 civilian guards to patrol inside the venues, but that number is likely to rise to up to 22,000, the source said.
The 6,000 troops would help meet the shortfall.
We'll all be reassured to know thousands of highly-trained troops are around, the source said.
The troops are not expected to wear military uniform, but most likely that of civilian security staff, and would receive their normal pay.
There were indications last month that more guards would be needed when LOCOG chief executive Paul Deighton told the London Assembly the deployment of army reservists was an option being considered to help meet the large number of guards required.
Britain remains on high alert of a terrorist attack despite its international threat level being lowered in July from severe to substantial, the third-highest level, meaning a terrorist attack is a strong possibility and might well occur without further warning.
Organisers are also wary of a potential threat from dissident Irish nationalists.
The Ministry of Defence have been fully involved in supporting Olympic security planning work, a government spokesman said in a statement on Friday.
We are committed to delivering a safe and secure Games that London, the UK and the world can enjoy.
He said the government had been working with LOCOG and G4S to finalise security requirements.
LOCOG's security budget has increased from an initial estimate of 29 million pounds to 432 million pounds.
Up to 12,000 police officers will also be deployed at peak times around the Olympic Park in Stratford, east London, and other venues.
The government's Olympic security budget has been reduced from a previous commitment of 600 million pounds to an estimated 475 million pounds.
The Olympic security coordinator Chris Allison has said police specialists could be used from forces across the country including firearms specialists, mounted police and protection and search officers.
While it was not intended for the armed forces to have a strong visible presence on Britain's streets during the Games, Allison has said it could provide niche capabilities such as Royal Navy boats on waterways.
Britain has been a terrorist target for many years, and its role in Iraq and Afghanistan, as a leading U.S. ally, has increased the threat posed by Islamic militants.
In July 2005, the day after London was awarded the Games, four young British Islamists killed 52 commuters in suicide bomb attacks on the capital's transport network.
(Reporting by Avril Ormsby)