A Commission note to these countries said it was prepared to invoke legal action at the European Court of Justice (ECJ) should piggeries in these six countries continue to seclude pregnant sows in separate stalls. EU directive 2008/120/EC says sows should be kept in groups "in order to improve the welfare of pigs", although a political decision to ban such individual stalls was taken as long ago as 2001. The rule became legally binding on 1 January 2013.
Final legal warning letters have been sent to Belgium, Cyprus, Greece and France, which have two months to explain how they will comply with the law or face a possible referral to the ECJ. Slovenia and Finland have been given more time to comply.
Last year, Brussels noted that member states had had "12 years to ensure a smooth transition to the new system".
ECJ judges have the authority to enforce a ban and, if its rulings are ignored, levy recurring fines on governments of potentially thousands of euros a day.