The European Commission is investigating whether big European pharmaceutical firms have colluded to fix prices in the vitamin market, according to a Commission source.

The news emerged as Roche Holding AG of Switzerland and Germany's BASF agreed to pay record fines for price fixing to the US Justice Department of $500 million (€470 million) and $225 million respectively.

Roche employs more than 200 people at its operation at Clarecastle, Co Clare. In the past, the plant has been in trouble for exceeding its emission levels.