Britain's Olympic body has urged the World Anti-Doping Agency to introduce mandatory four years bans for drug cheats as a minimum.

The current WADA code has a provision for four-year bans, but few federations opt to impose sanctions beyond the standard two years.

"(That) places in danger WADA's reputation and lays itself open to the question of how effective a global (non-governmental organization) can be in tackling the ever growing challenge of doping in sport," the British Olympic Association wrote to WADA in a document released Wednesday.

The 2012 Olympic host nation has submitted its proposed changes for the revision of the WADA code, which sets out drug-testing rules and sanctions across all sports and countries.

"Athletes globally are calling for tougher sanctions to rid sport of those that choose to cheat," the BOA said. "WADA should listen and act accordingly."

The BOA is the only Olympic body to impose life bans for dopers, but that would have to be scrapped ahead of the London Games if a Court of Arbitration for Sport ruling goes in WADA's favor later this month.

"Too often WADA has failed to catch the serious doping cheats — which, to its credit, WADA acknowledges," the BOA said. "Too often it is the law enforcement officers from individual countries who have led the war on doping in sport. Now may be the time to consider at a more fundamental level the role, structure and function of WADA as a centralized body."

Britain's anti-doping agency announced Wednesday that it has started testing international athletes in the country 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.

"We are doing all we can to ensure that there is no place to hide for drug cheats in this country," British Olympics minister Hugh Robertson said. "Information sharing across borders and a strong testing program will help in this fight."

In its submission to WADA, the BOA is also critical of the contentious "whereabouts rule" for out-of-competition testing. Some athletes claim their privacy has been invaded by the rule, which requires them to give advance notice of their whereabouts and be available for surprise visits for one hour each day.

"Too many athletes are treated, and feel, as if they are guilty before being proved innocent; yet often they are in the vanguard of the fight against cheating in sport," the BOA said.