The US Soccer Federation have argued the men's team are more skilful than the women's team in their fight to fend off an equal pay lawsuit.

The US women's team filed the suit last March before their World Cup victory in the summer.

But the country's governing body have now taken to comparing the skill level of the two sides as the reason that they pay the men more.

In a filing to the case, US Soccer said: "The point is that the job of [men's national team player] requires a higher level of skill based on speed and strength than does the job of [women's national team player]."

They also cited an academic paper 'Sex in Sport' by professor Doriane Lambelet Coleman which claims that it had 'indisputable scientific' proof that showed men's and women's teams don't perform at the same level.

The excerpt from Coleman's paper read: "The male body is different from the female body in many respects, but the differences that matter for sport go to power, speed, and endurance.

"They include skeletal structure, muscle composition, heart and lung capacity including VO2 max, red blood cell count, body fat, and the absolute ability to process carbohydrates."

Players from the women's team are seeking $66 million in damages from their governing body.

According to Buzzfeed, US Soccer's lawyer questioned players Alex Morgan and Carli Lloyd about the physical differences between men and women.

The lawyer said: "Do you think that the team could be competitive against the senior men's national team?"

Lloyd responded: "I'm not sure. Shall we fight it out to see who wins and then we get paid more?"

Morgan was then asked if men are more skilled, to which she replied: "No. It's a different skill."

The trial for the case is due to start in May.