LONDON (AFP) – Undercover guards will accompany British and American athletes at the Athens Olympics in August as part of unprecedented anti-terrorism measures, it was reported yesterday. But Greece, which will deploy more than 40,000 security staff during the Games, has ruled out foreign guards being armed. The London Evening Standard reported yesterday that British and US plain-clothes officers plan to watch competitors when they leave secure zones like the athletes’ village and sporting venues and go into public areas. Following the September 11 attacks on the United States in 2001, the Iraq War and last week’s Madrid train massacre, the Athens Games will be the most heavily guarded event in the 108-year history of the modern Games. While security at the 2000 Sydney Games was largely a police responsibility, the Athens Olympics will be dominated by a military operation which costs 650 million euros (820 million dollars), three times as much as four years ago. International Olympic Committee President Jacques Rogge said at the weekend the Madrid bombings had triggered another security review. And last week Greece asked NATO to provide aerial and sea surveillance against a chemical or nuclear attack. An international security exercise against terrorism has just started in Greece, involving 1,500 police and an overseas force of 400 American soldiers and 100 from Britain, Germany, Israel and Canada. Scotland Yard’s David Vennes, Britain’s top anti-terrorism official, has traveled to Athens to observe the «Shield of Hercules» exercise. It is understood that countries regarded as high risk – such as the USA, Britain and Israel – will be allowed to bring their own experts. Armed Greek guards will also be placed on team buses on their way to and from stadia. The Americans are expected to take at least 100 security agents with their team. Britain’s contingent will be smaller because they have fewer competitors.