The World Medical Association has called on its members not to implement new International Association of Athletics Federations (IAAF) regulations that restrict testosterone levels in female athletes with differences in sexual development.

The Court of Arbitration for Sport (CAS) this week dismissed an appeal by Olympic 800 meters champion Caster Semenya to set aside the regulations, which will come into effect on Wednesday.

However, the WMA, which represents physicians from 114 national member associations, said there was “weak evidence” that the regulations were necessary and that they should be scrapped.

“We have strong reservations about the ethical validity of these regulations,” WMA President Dr. Leonid Eidelman said in a statement on the organization’s website.

“They are based on weak evidence from a single study, which is currently being widely debated by the scientific community.

“They are also contrary to a number of key WMA ethical statements and declarations, and as such we are calling for their immediate withdrawal.”

Under the rules, female athletes with high natural levels of testosterone wishing to compete in events from 400m to a mile must medically limit that level to under 5 nmol/L, which is double the normal female range of below 2 nmol/L.

The IAAF has said no athlete would be forced to undergo surgery and that oral contraceptives should suffice in allowing them to reach the required level.

Testosterone increases muscle mass, strength and haemoglobin, which affects endurance.

Semenya will run in the 800m at the IAAF Diamond League meeting in Doha later on Friday, her final event before the regulations come into place.

The 28-year-old, along with Athletics South Africa (ASA), is considering an appeal to the Swiss Federal Tribunal, but after this weekend will have to run with blockers unless she moves up to longer distances.

CAS recognized in their verdict on Wednesday that the regulations were discriminatory, but added they were “necessary, reasonable and proportionate means of achieving the IAAF’s aim of preserving the integrity of female athletics in the Restricted Events”.

IAAF President Sebastian Coe reiterated the organization’s stance on Thursday at a media briefing in Doha.