Britain was last night preparing to retaliate after a UK trawler was detained by France amid fears the fishing row could spark a full-blown trade war. The Government accused the French of breaking international law and France's ambassador to London will be hauled in today to face questioning. Foreign Secretary Liz Truss said French ambassador Catherine Colonna would be expected to attend the Foreign Office 'to explain the disappointing and disproportionate threats made against the UK and Channel Islands'.... ...French ministers warned this week they will block British boats from some French ports and tighten checks on vessels travelling between...