All female athletes will be tested to prove their biological sex, World Athletics has said.
The sports governing body will introduce mandatory testing for anyone entering competitions in a move to protect the integrity of the sport.
It follows a series of high-profile scandals that have rocked track and field sports and comes two years after anyone assigned male at birth was banned from female events.
Competitors can elect for a non-invasive cheek swab, or a dry blood test that only have to be carried out once on an athlete.
The tests would verify if someone has transitioned to a female after going through male puberty, or if they had differences of sex development that provided testosterone advantages.
World Athletics President Lord Sebastian Coe said: “This we feel is a really important way of providing confidence and maintaining that absolute focus on the integrity of competition
“The pre-clearance testing will be for athletes to be able to compete in the female category.
“The process is very straightforward frankly, very clear and it’s an important one and we will work on the timelines.
“Neither of these are invasive. They are necessary and they will be done to absolute medical standards.”
Last summer at the Paris Olympics a row erupted after misinformation spread about Algerian professional boxer Imane Khelif about her gender and eligibility to compete.
Khelif, 25, won gold in the women’s 66kg event despite being embroiled in a gender eligibility row and received a torrent of abuse including death threats.
Many accused her of being a man – regardless of the fact that she was born female, is listed as female in her passport, and has never identified as transgender.
The International Olympic Committee [IOC] repeatedly asserted her qualifications to compete in the women’s division.
Khelif and Taiwan’s Lin Yu-ting were disqualified from the World Championships in 2023 by the International Boxing Association who said both fighters failed gender eligibility tests.
The International Olympic Committee cast doubt on the reliability of the tests and suggested what was happening is a “sometimes politically motivated cultural war”.
After her loss to Lin Svetlana, Kamenova Staneva of Bulgaria did a double XX gesture and pointed to herself – a reference to the female XX chromosome.
Khelif said: “I send a message to all the people of the world to uphold the Olympic principles and refrain from bullying all athletes, because this has massive effects. It can destroy people, it can kill people’s thoughts, spirit and mind. It can divide people. And because of that, I ask them to refrain from bullying.”
The IOC has previously called a return to sex testing a “bad idea”, but incoming President Kirsty Coventry is not ruling it out, having also talked about protecting the female category.
She said: “This is a conversation that’s happened and the international federations have taken a far greater lead in this conversation.
“What I was proposing is to bring a group together with the international federations and really understand each sport is slightly different.
“We know in equestrian, sex is really not an issue, but in other sports it is.
“So what I’d like to do again is bring the international federations together and sit down and try and come up with a collective way forward for all of us to move.”
US President Donald Trump has repeatedly stated there are only two sexes – male and female – while calling on sports to ban transgender women from women’s events.
In response to a post from American swimmer Riley Gaines, 24, saying “men don’t belong in women’s sports”, President Trump’s lieutenant, Tesla boss Elon Musk, 53, wrote: “Absolutely.”