* Nov exports down 2 pct y/y, imports down 5 pct y/y * Jan-Nov trade surplus more than doubles on the year * Euro zone southern periphery regains competitiveness By Martin Santa BRUSSELS, Jan 15 (Reuters) - The euro zone trade surplus widened in November because imports fell more sharply than exports, data from the EU's statistics office Eurostat showed on Wednesday, pointing to continued weakness of domestic demand. The 17 countries sharing the euro had an external trade surplus, unadjusted for seasonal swings, of 17.1 billion euros ($23.41 billion), in line with economists expectations. It was above the 12.5 billion euros in the same period of last year and a revised 16.8 billion euro surplus in October and for the first 11 months of 2013 it was 139 billion euros -- almost double that of the same period in 2012. Non-seasonally adjusted, exports from the euro zone fell by 2 percent on the year in November after a 1 percent rise in October, while imports dropped by 5 percent, following a 3 percent contraction in October. The United Kingdom remains the euro zone's key business partner with cumulative exports for the January to November period up by 3 percent and imports down by 2 percent. Exports to China, the bloc's third biggest trade partner after the second United States, were flat in the first eleven months of last year while imports fell 6 percent, leaving a 69 billion euro trade deficit, down from 78.7 billion in the same period of 2012. In a sign of rising competitiveness, exports of Europe's southern periphery countries -- Spain, Portugal and Greece -- were up by 4 percent in the January to November period, with cumulative trade deficits shrinking in all three year-on-year. Germany's trade surplus in the first eleven months of the year rose on the year, with flat exports and a 1 percent drop in imports, while France's deficit, shrinking year-on-year, was mainly due to a drop in imports.