Paris, France: World marathon record-holder Paula Radcliffe said she "supported" the International Association of Athletics Federations (IAAF) in their controversial attempt to restrict female athletes' testosterone levels.
"It's a very, very difficult and complex situation and I don't feel there is an outcome that is perfectly fair to everybody," the now-retired British runner told AFP in Paris on Friday.
The IAAF is seeking to force so-called "hyperandrogenic" athletes or those with "differences of sexual development" (DSD) to seek treatment to lower their testosterone levels below a prescribed amount if they wish to continue competing as women.
"These guys haven't chosen," Radcliffe said.
"It's just the way they are born, and the way they have grown up. At the same time the results are clear to see and we have the data evidence that it's not a fair situation.
"Maybe in the future there will be more than two categories."
The Court of Arbitration for Sport is wrestling with an appeal against the rule by Caster Semenya, the South African Olympic 800-metre champion.
"Female sport has its definition and its category for a reason. Because women could not compete with men," the 45-year-old Radcliffe said, adding she believed the IAAF "are trying to protect female sport and create fair competition. But I do see it's a very, very difficult decision for CAS to be able to take."
"I think other sports are watching to see what happens because it also affects them," Radcliffe said.
South Africa's sports minister Tokozile Xasa has accused the IAAF of pursuing "the violation of women's bodies."
Radcliffe was sympathetic but argued the alternative was also unfair.
"It's not possible to be fair to everybody," she said.
"I don't think the IAAF are saying you must modify your body. You must bring your testosterone down if you want to compte in female category. Otherwise you're free to compete at non-elite level or in the male category."