ATHENS (Reuters) - Spanish telecoms provider Telefonica (>> Telefonica SA) has offered concessions in a bid to secure European Union antitrust approval for its proposed takeover of KPN's (>> KPN KON) E-Plus unit in Germany, the European Commission said on Friday.

The 8.6-billion-euro ($11.94 billion) deal could spur more consolidation in the telecoms sector, which faces its fifth year of declining revenues in 2014. However, this could be held back if regulators demand stringent concessions in return for their approval.

The EU competition authority said it would decide on Telefonica's bid by June 23. It did not provide details, in line with its policy.

Telefonica Deutschland (>> Telefonica Deutschland Holding AG) declined to comment on the concessions.

"We remain confident that we will get merger clearance in the second quarter," spokesman Albert Fetsch told Reuters by telephone.

Rivals such as German telecoms and Internet services provider Freenet (>> freenet AG) and United Internet (>> United Internet AG) say Telefonica should be forced to give competitors cost price access to its German network and sell some of its prepaid brands.

E-Plus competes with market leaders Deutsche Telekom (>> Deutsche Telekom AG) and Vodafone (>> Vodafone Group plc).

($1 = 0.7204 Euros)

(Reporting by Foo Yun Chee; editing by Robin Emmott)