(Telecompaper) The European Commission has blocked the proposed merger of O2 UK and 3 UK, saying competition on the UK mobile market would suffer with only three network operators. The decision is in line with calls from UK regulator Ofcom to maintain four players and follows lengthy negotiations with 3's owner CK Hutchison over possible concessions to maintain competition. Hutchison agreed the takeover of O2 from Telefonica in March 2015 for GBP 10.25 billion. The deal would have led to 3 UK jumping from fourth to first place on the UK market.