Eight manufacturers of bulk vitamins are facing fines amounting to €855.22m (US$752.16m) after the European commission found them guilty of violating antitrust laws.

The worst offenders in the price-fixing cartel were German chemicals group BASF and Swiss pharmaceutical giant Hoffmann-La Roche, who received penalties of €296.16m and €462m respectively. Roche was identified as "the prime mover and main beneficiary of these schemes", and thus given the highest cumulative fine.

The other disgraced companies are Takeda Chemical Industries (now part of BASF) (fined €37.05m), Daiichi Pharmaceutical Co (€23.4m), Eisai Co (€13.23m), Merck KgaA (€9.24m), Solvay Pharmaceuticals (€9.10m), and French biotech giant Aventis (€5.04m).

Announcing the fines on Wednesday, the European Competition Commissioner Mario Monti had harsh words for the guilty companies. "This is the most damaging series of cartels the Commission has ever investigated due to the sheer range of vitamins covered," he said: "The companies' collusive behaviour enabled them to charge higher prices than if the full forces of competition had been at play, damaging consumers and allowing the companies to pocket illicit profits.

"It is particularly unacceptable that this illegal behaviour concerned substances which are vital elements for nutrition and essential for normal growth and maintenance of life."

Responding to the EC judgement, both BASF and Roche said they were reviewing the decision to decide whether to lodge an appeal with the European Court within the two-month legal time limit.

Separate statements issued on Wednesday by both companies also stressed the enforcement of internal measures designed to combat the violation of antitrust laws; including staff training in legislation and regular audits.