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* In Amenas output down since 2013 militant attack
* Third gas train in test production last week
* Output to increase as EU, Algeria talk energy (Adds details on production, background)
By Lamine Chikhi
ALGIERS, May 25 (Reuters) - Algeria's In Amenas gasprocessing plant started test production at its third train aweek ago and will soon be back running at full capacity, morethan three years after a militant attack, a source at stateenergy firm Sonatrach said on Wednesday.
The plant's second train is in scheduled maintenance, but InAmenas should be back to its full 9 billion cubic metres (bcm)annual production capacity by late June for the first time sincethe 2013 attack that killed 40 oil workers and hit output.
The return to production at In Amenas, which supplied around11.5 percent of Algeria's total natural gas output before theattack, comes as Algeria and the European Union are in talksabout improving energy cooperation to diversify E.U. supplies.
"Test production has been launched successfully, and theofficial opening is expected very shortly," a top Sonatrachsource, who asked not to be named, told Reuters.
"In the third week of June the plant will come back to fullproduction at 9 billion cubic metre per year."
In Amenas is operated by BP, Statoil andSonatrach. Sonatrach engineers have been managing the plantsince BP and Statoil pulled out workers following a rocketattack in March on the Krechba gasfield.
European Union officials and industry representativesattending a business forum in Algiers on Tuesday urged Algeriato adapt to more competitive markets and attract the investmentneeded to pump more gas north again after years of slidingexports.
Algeria is seen as a natural source of gas supplies for theEuropean Union after the Ukraine conflict underlined the risksof relying too much on the bloc's top gas supplier, Russia.
While the North African country is the EU's third biggestgas supplier behind Russia and Norway, its export capacitythrough three pipelines and LNG shipments across theMediterranean Sea is underused.
Algeria's government hopes dozens of projects, mostly inits southwestern Sahara will generate new production and helpkeep its flow of gas to Europe stable in the medium term. But ithas failed to attract the investment needed to discover anddevelop new fields and maintain old ones. (Writing by Patrick Markey; Editing by Greg Mahlich)
