European Union antitrust authorities have objections regarding the current version of the proposed €8.6 billion deal for Telefonica to buy KPN’s German mobile unit E-Plus, Bloomberg reported.

The EU body will send a formal list of concerns to the companies, which should make it clear what steps they must take in order for the deal to be approved.

The European Commission started to investigate the deal in December last year, expressing concern that it would reduce competition in the German mobile market and lead to higher prices.

The deal would reduce the number of mobile operators in Germany from four to three, with E-Plus combining with Telefonica’s O2.

The EU objections are likely to lead to concessions being offered by Telefonica Deutschland. These could include promises to help new operators enter the market, a move that helped Hutchison Whampoa secure approval for its 2012 acquisition of Orange in Austria.

The E-Plus deal has been subject to a regulatory tug of war between the European Commission and German competition authority, with the former deciding to retain responsibility in January.

The commission said it should oversee the deal due to its past experience with major mobile deals and a need for consistency in how M&A rules are applied across the European Union.

The German authority had reminded the commission of a previous request it made to take on the deal in November 2013 on the grounds that a deal’s effects are restricted to a single, national market.

The commission has until 14 May to make a decision on the proposed deal.