The three major networks hope to develop a mobile wallet project that uses a pay as you go system on NFC chips that allow users to 'tap and pay' in shops and cafes.
Regulators are yet to give Vodafone, Everything Everywhere and O2 the go ahead, but Three isn't hanging around, having filed the legal action with the EU's antitrust authorities.
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Stephen Lerner, Three's general counsel, describes the networks' consortium as a "cosy collaboration" and said that the EU "should not allow this type of collaboration to go forward under any circumstances.
"Excluding the maverick raises serious competition concerns. It has serious implications for both consumers and wider business as the internet continues to move mobile."
NFC is on the cusp of taking off in a big way, with Google throwing its weight behind the technology and Apple rumoured to be including an NFC chip in the new iPhone 5; clearly the UK's mobile network operators want a slice of the NFC pie.