The European Union raised the stakes in a series of tit-for-tat trade disputes with China, saying it would file a complaint at the World Trade Organization over Chinese tariffs on imported EU stainless steel pipes. EU Industry Commissioner Antonio Tajani told French radio station Europe 1: \"The European Commission is going to lay a complaint before the World Trade Organization concerning China.\" Tajani gave no further details but a European source in Geneva, home of the 159-nation WTO, said earlier that a complaint was due to be filed by the end of the week.