Slapping extra tariffs on cheap “dumped” imports can be counter-productive even when justified, the European Union’s trade chief said on Monday, just weeks before he proposes reform of the bloc’s trade defence system.

Peter Mandelson, the EU trade commissioner, told a conference in the Netherlands that anti-dumping tariffs and quotas could harm Europe’s own manufacturers, which have increasingly outsourced the production of shoes, textiles, lightbulbs and other goods, aiming to maintain a competitive edge against cheaper Asian rivals.