Riders at the Tour de France Femmes Avec Zwift have had their clothing checked to prevent attempts to make "aerodynamic gains".

Issues have reportedly been raised about padding in bras that could result in riders gaining one second per kilometre.

Race organiser ASO issued a statement following Dutch media reports of concerns some riders had used bra padding as aerodynamic fairings to improve efficiency.

Other items have also been known to be inserted into a skinsuit around the chest area to smooth airflow around the body.

"Riders must be to the final checks before the race (bikes and outfit) no later than 10 minutes before their respective start time," the statement said.

"Particular attention will be paid to compliance with article 1.3.032 of the UCI regulations, including non-essential elements and clothing or other items/accessories worn by a rider (including but not limited to helmets, glasses, shoes or in-race communication devices) which could modify riders' morphology."

Dutch outlet Wielerflits, external said the practice had been seen previously in women's cycling, including at the Paris 2024 Olympics.

Riders could face disqualification from a race and a fine of nearly £200.

Much attention is paid to airflow and aerodynamic efficiency in cycling as the correct shape of bike frame and skinsuit can save a rider several seconds, especially during a time trial - where a rider races alone against the clock.

In ski jumping last February, male athletes were accused of using penis injections to aid aerodynamic efficiency.

Cycling's world governing body the UCI's rule also says it prohibits clothing "not strictly necessary for the functionality of the clothing, or other item, or accessory".

"The problem is how are you going to police it?" Lidl-Trek's head of technical and innovation, Koen de Kort, told The Athletic., external

"That's the biggest issue. You can say it's not allowed [but] how can you say how much a woman needs?

"That's time to get pretty much into a grey area of what you're allowed to check."

In a study by researchers at universities in Scotland and the Netherlands, a mannequin of a male rider, 177cm in height, inside a wind tunnel found fairings can give rise to "significant drag aero reductions" and that wider objects yielded the largest gains.