* October exports up 1.0 pct y/y, imports fall 3 pct y/y
* Southern periphery regains competitiveness
* Euro zone Jan-Oct surplus more than doubles y/y
By Martin Santa
BRUSSELS, Dec 16 (Reuters) - The euro zone's external trade surplus almost doubled year-on-year in October, data showed on Monday, thanks to a modest rise in exports and a fall in imports which point to rising euro zone competitiveness but still weak domestic demand.
The trade surplus for the 17 countries sharing the euro, unadjusted for seasonal swings, was 17.2 billion euros ($23.62 billion) in October, compared with 9.6 billion euro surplus in the same period last year.
The trade surplus of the 9.5 trillion euro economy more than doubled in the first ten months of the year to 122.8 billion euros compared with 57.4 billion euros in the same period of 2012, data from the EU's statistics office showed.
Non-seasonally adjusted, exports from the euro zone rose by 1 percent on the year in October after a 3 percent increase in September, while imports fell by 3 percent, following a 1 percent rise in September.
In a sign the southern periphery was regaining competitiveness, crucial for balancing the fragile economic rebound in the single currency area, Portugal saw exports rising 4 percent in the first nine months and exports from Greece and Spain were up 5 percent.
The United Kingdom, flirting with the idea of leaving the European Union after a planned 'in-or-out' referendum in 2017, remains the bloc's biggest trade partner both in terms of exports and imports.
Seasonally adjusted exports from Germany, Europe's largest economy, fell 0.9 percent in October, which was counterbalanced by a 1.0 percent decline in imports.
The euro zone recovery almost stalled in the third quarter after a return to growth in the second quarter.($1 = 0.7283 euros)