BRUSSELS--European Union antitrust authorities gave the final nod of approval to Telefonica SA's EUR8.6 billion ($11.7 billion) takeover of German mobile operator E-Plus on Friday, confirming the conditions discussed earlier this year are acceptable.

Telefónica Deutschland has agreed to sell upfront 20% of its mobile network capacity to smaller local rival Drillisch AG.

"Drillisch meets the purchaser criteria set out in the commission's decision and the agreements between Telefónica and Drillisch also comply with the commitments," said Antoine Colombani, spokesman for EU Competition Commissioner Joaquín Almunia.

The merger has been something of a test case for how EU authorities are looking at mergers and acquisitions in Europe's rapidly consolidating telecoms sector. The deal reduces the number of mobile operators in Germany from four to three.

The European Commission, which acts as the region's central antitrust authority, gave the green light initially in July, confirming the details Friday.

Telefónica Deutschland said it would close the acquisition during the third quarter of 2014.

Write to Frances Robinson at frances.robinson@wsj.com

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