At least 674 people were fitted in Belgium with potentially faulty breast implants made by French firm PIP, nearly seven times more than previously estimated, the health ministry said Monday.

About 300,000 women in 65 countries are estimated to have received implants made by PIP, which allegedly used an illegal industrial-grade gel that investigators say has led to abnormally high rates of ruptured implants.

Health authorities in Belgium had previously stated that around 100 women had PIP implants. Four of them have had them removed since the beginning of December while a fifth woman plans to do so.

On December 23, the Belgian authorities advised women with implants from Poly Implant Prothese (PIP) to go for a check-up and have them removed if there was any sign of seepage or rupture.

The Federal Agency for Medicines and Health Products "estimates that 674 people in Belgium have PIP implants," the health ministry said in a statement, adding that it could not guarantee the accuracy of the figure or indicate the nationality of the patients.