Olympics organisers have been allocated £280m by the government to beef up security at venues being used in 2012.
The sum, part of the overall £9.3bn Games budget, will fund measures such as bag screening, fencing and perimeter searches at the various UK venues.
Separately, the £600m Olympic safety and security budget could be trimmed to £475m thanks to Home Office savings.
Security Minister Baroness Neville-Jones insisted: "Olympic safety and security has been prioritised."
The coming year will see venues handed over to London 2012 as the organisers press ahead with test events and plans to stage the games.
Although much of the Games' focus will be on the new Olympic Park at Stratford, east London, several other locations are hosting events.
Football stadia being used include Cardiff's Millennium Stadium and Hampden Park in Glasgow, while other sports taking place outside London include sailing at Weymouth, Dorset, and mountain biking in Essex.
Releasing the extra money and the potential future savings is not expected to compromise plans or put the public at risk, a Home Office spokesman said.
Responsibility for venue security is split between London 2012 and the government.
In a statement to the Lords, Lady Neville-Jones said safety and security for the 2012 Games is well advanced and on schedule.
Some £600m was budgeted for the core Olympic security programme in 2007 and the government said it would still make this sum available, although savings identified could bring the total spend down to about £475m. This does not include the £280m for venue security.
Beyond the £134m which will have been spent by the Home Office by the end of the current financial year, the Home Office will provide £107m in 2011/12 and £192m in 2012/13, primarily for the police service to meet Olympic safety and security costs.
This is on top of core police funding and the contributions being made by other government departments.
The statement to Parliament says: "Home Office funding includes a very substantial financial provision for contingencies."
A further Olympic contingency of around £500m is available for cross-programme issues, which could address any "material change" in the security situation, it says.
Much of the £1.1bn being set aside for counter-terrorism policing will be devoted to the Olympics in 2012, the statement adds.