Police arrested two men on suspicion of preparing terrorist attacks in Britain, less than a month before the opening of the London Olympic Games in the British capital.

Seven years after suicide bombers killed 52 people in a string of coordinated attacks in London, British security forces are on high alert for any signs of trouble ahead of the Games, which start on July 27.

London police said the two men, aged 18 and 32, were arrested by officers from its Counter Terrorism Command on suspicion of terrorist-related activity, Reuters reports.

"Both (are) in custody at a central London police station," it said in a statement. Police declined to give further detail.

Police and military strategists are gearing up for a range of security threats at the Olympics including bomb explosions, violent protests and attacks using hijacked airliners.

Around 13,500 soldiers are expected to help the police during the Games, which run from July 27 to August 12.

Security is a big worry in Britain, a country with an ethnically diverse population and which backed the U.S. invasion of Iraq and still has troops deployed in Afghanistan.

Yet many Londoners are already weary of the increasingly tight security measures, with some accusing defence officials of creating a climate of fear and running the risk of disrupting the daily course of life for many ordinary people and commuters.