The World Anti-Doping Agency could investigate if evidence emerges that male ski jumpers are injecting their penises in a bid to improve sporting performance.

In January, German newspaper Bild, external reported that jumpers were injecting their penises with hyaluronic acid before being measured for their suits.

Hyaluronic acid, which is not banned in sport, can be used to increase penis circumference by one or two centimetres.

This would increase the surface area of their suits during competition, which, according to FIS, the international ski and snowboard federation, could increase their flight in the air.

"Every extra centimetre on a suit counts. If your suit has a 5% bigger surface area, you fly further," said FIS ski jumping men's race director Sandro Pertile.

Asked about the claims in Bild at a press conference at the Milan-Cortina Winter Olympics, Wada director general Olivier Niggli said: "I am not aware of the details of ski jumping, and how that could improve performance. 

"If anything was to come to the surface, we would look at it and see if it is doping related. We don't address other [non-doping] means of enhancing performance."

Clearly entertained by the question, Wada's Polish president Witold Banka joked: "Ski jumping is very popular in Poland so I promise you I'm going to look at it."

FIS communications director Bruno Sassi told BBC Sport: "There has never been any indication, let alone evidence, that any competitor has ever made use of a hyaluronic acid injection to attempt to gain a competitive advantage."

Before the start of each season, ski jumpers are measured using 3D body scanners, in which they must wear only "elastic, body-tight underwear". 

Rules state their suits must have a tolerance of only 2-4cm, and as part of the measuring process, their crotch height is also measured.

The crotch height of their suit must conform to the athlete's crotch height, with the addition of 3cm for men.

Hyularonic acid injected into the penis can last up to 18 months.

There have been previous attempts to improve performance through manipulations of the suits.

In August, Norwegian Olympic medallists Marius Lindvik and Johann Andre Forfang accepted three-month suspensions for their part in the tampering of suits during the men's large hill event at the World Ski Championships in Trondheim, Norway, in March.

While it later transpired the athletes themselves were not aware of the tampering, FIS said their team had "tried to cheat the system" by putting reinforced thread in their jumpsuits.

Both athletes are set to compete at these Winter Olympics, which officially start on Friday.

The men's ski jumping competition begins on Monday.