Fibres are then extracted from the dough and wound into enormous 900lbs bales before being spun to make the fabric called Lenpur. Designers have said the process is similar to the traditional art of spinning cotton.

A small amount of lycra is added in to make the undies feel more comfortable and to help maintain their shape. The range is called g=9.8 which is the scientific figure for the earth's acceleration due to gravity.

They are on sale in the UK via the internet with prices starting from 25 for a pair of pants.

Sophie said: "My child developed an allergic reaction and asthma which was partly triggered by dyes, chemical products and pesticides.

"I am a member of the Association Asthma and Allergies in France and wanted to create a line of lingerie respectful of the environment.

"All the wood used to make the range is cultivated and then broken down with the use of enzymes. Enzymes are proteins which transform a raw material A to another material B, similar digestion with beer.

"The wood turns into a dough in which fibres can be extracted. The entire process takes between several hours to a few days.

"Bales of fibres, of a weight of about 900lbs, are assembled and spun by a traditional process, similar to that of cotton.

"The fabric is dyed in many different colours but we guarantee harmlessness in respect of irritation and allergies.

"The underwear can be washed in a machine at 30C but we they are not suitable for tumble drying as it is not ecological.

"Wood fibre offers the comfort of silk, the touch of cashmere and the lightness of linen.

"We introduced the first line at an ethical fashion show in Paris and in Lyon Mode city in Lyon.

"Now the British company Bynature sell my underwear online and others have asked for my linesheets."