The British government approved a security strategy for the London 2012 Olympics on Thursday which it says will stay within the 600 million pounds ($854.7 million) budget even though experts argue it could cost double that sum.

Interior Minister Jacqui Smith said a strategy had been devised on how to achieve a "safe and secure Games in keeping with the Olympic culture and spirit".

Full details of the plan, which would cover the Olympic venues, events and infrastructure, including transport, will not be made public though.

Smith assured lawmakers in a written statement the plan would not break the security budget, and the government was on course not to tap into the 238 million pound contingency made available in December 2007.

"This 600 million pounds, together with a contingency of 238 million on which there are currently no plans to draw, and the security budget of the Olympic Delivery Authority (ODA) are parts of the overall Olympic public sector funding package of 9.325 billion pounds," she said.

The ODA has a budget of 354 million pounds for security during the construction of the site.

The Safety and Security Strategy, as well as an accompanying draft Concept of Operations, will also draw on the government's "substantial investment in counter-terrorist and other security, law enforcement and resilience measures", she added, without giving a figure.

Security costs for the Vancouver 2012 Winter Olympics have risen five times to C$900 million since its bid.

Former senior Metropolitan police officer Tarique Ghaffur, who had been responsible for the early planning of Olympic security, told the Daily Telegraph last December the government would have to "throw money" at it because of delays in planning.

Insiders were quoted in London's Evening Standard as saying anti-terrorism measures could push the bill to 1.5 billion pounds.

Smith said international partners would be consulted on security planning for London.

The plan is designed to respond flexibly to changes in risks and to deal with any unexpected events in the run-up to the Games, she said.

A dedicated Metropolitan Police specialist team has been established to police the Park and prevent economic crime, while the capacity of the digital radio communications system, Airwave Tetra, has been boosted to ensure the system remains resilient in the case of any emergency.