Irish swimmer Barry Murphy is calling for swimming authorities to follow the lead of cycling and introduce biological passports to stop swimmers who are taking performance-enhancing drugs.

"There are certain things going on in the sport and you can almost go into the locker room back there and point out who is doing it," Murphy said after his elimination from the 50m freestyle last week. "Just by their physique, and the way a swimmer races, you can tell who's at it."

According to the Irish Independent, FINA, the world swimming body, announced last week that they planned to introduce a pilot project using biological passports.

"There are guys who are in there, who are failing tests and they are not even getting suspensions, they are just getting warnings and that is a disgrace," Murphy said. "I have always pushed for a clean sport, I think it is essential. If you can't win anything cleanly, then it is not worth winning."

Last year, Brazilian Cesar Cielo, who took bronze in Murphy's event on Friday night, tested positive for a banned substance, which is prohibited as it's often used as a masking agent.

The Irish Independent reports that FINA had challenged the decision of the Brazilian doping authorities, who only to give Cielo a warning. However, the Court of Arbitration for Sport upheld the decision and stated that FINA accepted Cielo did not take the drug to enhance his performance. The athlete himself said that he had taken the drug in a contaminated batch of a food supplement he took regularly and that a pharmacy was blamed for the contamination. Shortly after the positive test, Cielo won gold at the World Championships in Shanghai.

"Of course it is disheartening. There are guys who are going into the 50-free semis and final who have failed tests and they are still here," said Murphy. "People know who they are, so it is frustrating when you are trying to do it the right way. But it is not up to me or anyone else to tell those guys they shouldn't be here. It is up to WADA and FINA to catch them and implement the proper sanctions.

"I'm in the pool six hours a day, putting my heart and soul into this sport, trying to eat right, trying to live as healthy a life as possible and there are other guys who are just doing it the easy way. Everyone could do it the easy way if they want. But it's not like that, it can't be like that for our sport." Murphy still believed the good in swimming outweighed the bad.

"The negativity can be detrimental to the sport, but then people see Phelps winning 22 medals and that is going to inspire kids to take up the sport -- it inspires me to be a better swimmer. There are good and bad in all sports and it affects sports in different ways."