Britain's anti-doping agency says it has started testing international athletes in Britain ahead of the London Olympics.
Intelligence has been gathered from international sports federations and national anti-doping organizations to target athletes who are in Britain to train or compete before the July 27-Aug. 12 Olympics.
Athletes can be tested without notice.
British Olympics minister Hugh Robertson says "we are doing all we can to ensure that there is no place to hide for drug cheats in this country. Information sharing across borders and a strong testing program will help in this fight."