SYDNEY (REUTERS) - Tennis great and gay rights trailblazer Martina Navratilova has slammed the International Olympic Committee (IOC) for its lack of leadership on the issue of the inclusion of transgender athletes in sport.

The issue was brought into focus by last weekend's decision by swimming's governing body Fina to ban athletes who have been through any part of male puberty from elite women's competition.

The IOC last year revised its guidelines on inclusion with a new framework, advising that athletes should not be excluded from competition on the grounds of "perceived" unfair advantage, but leaving it up to sports federations to decide the rules.

Navratilova said that striking the balance between inclusion and fairness down to individual events was extremely complex and that the IOC had offloaded responsibility for the issue onto sometimes poorly funded federations.

"The IOC has completely punted," the 59-time Grand Slam champion told The Australian newspaper.

"That 'Oh, we will leave it up to the individual federations'. How can these individual federations within their country make their different rules?

"They have to do the research and the implementation ... and it costs money to then figure it out, and it's impossible."

While Fina engaged leading scientists on the task force which drew up its rules, advocates for transgender inclusion argue that not enough studies have yet been done on the impact of transition on physical performance and that elite athletes are often physical outliers in any case.

LGBT rights group Athlete Ally said Fina's new eligibility criteria was "discriminatory" and "harmful", while transgender cyclist Veronica Ivy described the policy as "unscientific".

Navratilova, who famously employed transgender coach Renee Richards during her glittering playing career, said she thought the Fina decision had been a welcome pushback.

"It's been such a topsy-turvy situation ... with the momentum totally on the side of the transgender athletes," Navratilova told the newspaper.

"When it comes to sports, biology is the biggest divider ...

"So Fina, it's the first big organisation that has gone all in for fairness and maybe it will try to include as many people as possible, as is fair. But fairness has to be first ..."

There was no immediate reply to a request for comment on the matter from the IOC.

Meanwhile, some American athletes said there were no easy answers on the matter of transgender participation in elite sport, days after World Athletics said it was reviewing its policies, with twice world silver medalist Sandi Morris suggesting a new category.

Besides voting to restrict the participation of transgender competitors in women's competition, Fina had at the same time proposed establishing an "open" category, a move widely opposed by LGBT rights advocates.

The next day, World Athletics president Sebastian Coe said the organisation would discuss its own regulations at the end of the year, telling the BBC: "We have always believed that biology trumps gender."

Olympic silver medal-winning pole vaulter Morris said she supported the transgender community but that athletes were put in a "tough position" on the topic.

"I do believe that maybe the best answer is to come up with a way to have another category," she told Reuters on Wednesday (June 22), ahead of this week's US championships.

"Athletes like myself who are liberal and liberal-leaning, we're not quick to get in bed with people who are hateful toward people of those communities.

"So I think that there is a solution, but we need to figure out what."

Allyson Felix, the most decorated American in track and field history, said it was a complex issue.

"We're dealing with people and people's lives," said Felix, who is competing in her final U. championships before retirement.

"I don't have the answer. I think it is a tough one."

The US track and field championships, the main qualifying event for the World Championships, kick off on Thursday.