French drugmaker Sanofi-Aventis won European Union regulatory approval on Wednesday for its hostile $18.5 billion takeover bid for U.S. biotech firm Genzyme.

The European Commission, the EU competition watchdog, said a deal would not significantly reduce competition in Europe.

"The Commission's examination has shown that the proposed transaction would not lead to significant combined market shares in the product categories where the parties' activities overlap," the EU watchdog said in a statement.

"In addition, the proposed transaction also does not raise concerns in the treatment of multiple sclerosis, where both parties are developing treatments. In all cases there will remain a sufficient number of other credible competitors," it added.