Rules that bind athletes to give details of their daily movements to drugs testers are not being enforced in "half the countries in the world", it was claimed on Thursday.

The revelation will be particularly controversial in Britain after last week's news that a pool of 30 top Premier League footballers will have to provide details of their daily whereabouts - even when on holiday - to anti-doping officials.

The issue is likely to be top of the agenda of the World Anti-Doping Agency's (WADA) board meeting in Montreal this weekend after a survey carried out during the Beijing Olympics revealed the discrepancies.

Sir Craig Reedie, British IOC member and a board member of the WADA, said "half the world'' was not operating the system properly - WADA regulations state that athletes must provide testers with their whereabouts for an hour each day.

Reedie said: "The one issue the world of sport will want clearing up is in relation to whereabouts regulations for athletes.

"What has come out of Beijing is that half the world operates the system properly and half the world does not.

"This has come out of a survey done of national Olympic committees, and some are struggling with the whereabouts rules.

"We have to get the system to work properly so that everyone is operating in the same way.''

Three British athletes have already picked up bans for not being around on three occasions when drug testers called. They are 400m runner Christine Ohuruogu, triathlete Tim Don and judo player Peter Cousins.

Plans for the Premier League's top stars to be tested for drugs in their own homes from January have been opposed by the Professional Footballers' Association as "an invasion of privacy".