The founder of a French company was sentenced to four years in prison by a Marseille criminal court on Tuesday for hiding the true nature of the sub-standard silicone used in implants sold to 300,000 women around the world, Fox News reports. 

The sentence was for Jean-Claude Mas, 74, founder and long-time chief executive of Poly Implant Prothese (PIP).

The company was shut in 2010 and its implants ordered off the market after inspectors pursuing a tip-off discovered vats of industrial-grade silicone outside the PIP factory in southern France.

Mas, who had been pursued for aggravated fraud, was also ordered to pay a 75,000-euro ($103,000) fine. His lawyer, Yves Haddad, said he would appeal.

Four other executives, including the chief financial officer, were sentenced to between one and a half and three years in prison, some of it suspended, and fined.

Mas has admitted using silicone that was never approved by regulators but has insisted the gel he had used since the founding of the company in 1991 was non-toxic.