The French head of the company at the centre of the international breast implant scare was employed by a second firm making medical prosthetics set up by two of his children.

Jean-Claude Mas, the founder of Poly Implant Protheses (PIP), the firm accused of using cheaper industrial silicone rather than approved medical material in its implants, is listed as a "technical and commercial consultant" to the new company, set up eight months after his own firm was closed down.

According to confidential documents leaked to the French newspaper Nice-Matin, the second company, France Implant Technologie (FIT), was registered in June to Nicolas Lucciardi, 27, and his 24-year-old sister Peggy and registered at the address of their mother, Dominique Lucciardi, Mas's former partner.

Official company records lodged with the local authorities describe FIT as a "company making medical-surgical and dental material", but Nice-Matin says the leaked documents it has show the firm's "business plan" was to make breast implants.

The plan described Mas, 72, as a "creative genius" and says its collaborators have "30 years of experience in the field of quality, research and development, production and commercialisation of breast implants".

It stated its aim was to produce 400 silicone gel implants every day at the former PIP production site in the south-east of France, to be sold to "the European, South American and Chinese market". The manufacture of breast implants was due to start in June next year and reach a turnover of €6m (£5m) a year, according to the reports.

Two other former PIP executives were also listed as company employees responsible for production and quality control. There is no suggestion the company had yet produced a single implant or done anything illegal.

More than 300,000 women worldwide are believed to have been fitted with PIP silicone implants, which at the height of its business was the third-largest manufacturer of breast implants in the world.

PIP was forced to stop trading in October after being investigated by the French health authority AFSSAPS for allegedly producing substandard implants. Earlier this week it was revealed that the American Food and Drug Authority had warned PIP that saline breast implants it was producing were "adulterated" and did not meet medical quality requirements 11 years ago.

The health authorities in France have advised the 30,000 French women fitted with PIP silicone implants to have them removed but insisted this was "precautionary" rather than "urgent".

In Britain, where about 40,000 women are believed to have PIP implants, medical officials say there is no evidence they are a health risk, but have advised the women to see their doctor for checks.

Mas is under investigation for "aggravated cheating" following an investigation into the quality of PIP implants.

A second preliminary inquiry has been opened into a possible case of "manslaughter" after the death of a woman who was given PIP implants.

About 2,500 women fitted with the implants have registered complaints with the court in Marseilles.

Nine French women with PIP implants were found to have a rare form of cancer and there are allegations the implants are prone to rupture.