The Maori Spectrum Coalition says the public should be very worried about the auction of the remaining 4G radio frequencies.
The Government will auction off the last block of 4G spectrum on Tuesday. It has ignored the Waitangi Tribunal's recommendation to allocate a portion to Maori.
Telecom, Vodafone and 2degrees have so far secured slices of the 700-megahertz band, which will be used for a new generation of mobile phone technology.
Coalition spokesperson Antony Royal says people should be concerned because the auction will only attract overseas companies with deep pockets who will do nothing with it.
He says the only reason companies will buy it is so they can lock out competitors.
Mr Royal says when Maori bought a block of 3G spectrum, it created 2degrees which has brought down national mobile costs.