The U.S. seems wary about the security arrangements for the 2012 London Olympics in the wake of the riots in some of parts of England this summer and arrests made at the Games site.

According to the Guardian, the U.S. is planning to send up to 1,000 commandos, including 500 FBI agents, to ensure the safety of its contestants and diplomats.

Some U.S. officials also expressed discomfort over the restrictions imposed by the UK on anti-terrorism "stop and search" powers. They have also sought classified details of the number of British police and security personnel to be made available during the London 2012 Games.

British politicians including Prime Minister David Cameron, Home Secretary Theresa May and Culture and Sport Secretary Jeremy Hunt are now being questioned by the U.S., the report said. The UK is apparently irked by the constant meddling by the U.S. and the demand for answers seeking reassurance.

"We are not equal partners in this. They are being very demanding," the newspaper quoted one security official as saying.

There's mounting pressure on the London Organising Committee of the Olympic and Paralympic Games too. According to the report, the committee is trying to pre-empt a potential crisis in terms of venue security. The original idea was to deploy 10,000 guards, but after a review it was decided that 21,000 guards would be needed, the report said.

Despite the UK lowering the threat of a terror attack to its third level, U.S. intelligence officials are apparently not convinced, the newspaper said. They fear that U.S. participants in the Games are likely to become possible "soft targets" for terrorists.

According to a Whitehall source, the entire Olympic security operation was being prepared "with the U.S. in mind," adding: "The U.S. will have no qualms in saying it is unsafe. If something happens and we say we did not have enough people, we are finished," revealed the report.

At present, the Ministry of Defence and the Home Office have not taken any final decision on the number of security guards at some of the Olympic sites. But, the Home Office and Scotland Yard believe that the UK has a robust security strategy.

Meanwhile, the U.S. State Department declined to comment on the matter.