Ofcom wants to bar BT/EE from bidding in part of a forthcoming spectrum auction because the UK regulator is wary of the market leader’s growing dominance.

Under the proposal, BT/EE would not be allowed to bid for 40MHz available in the 2.3GHz band.

BT/EE currently holds 45 per cent of immediately useable UK mobile spectrum, said the regulator. Vodafone holds 28 per cent, O2 15 per cent and Three 12 per cent, and all have no restriction on their bidding.

The regulator is concerned that if the country’s spectrum holdings became further unbalanced in coming years, it could damage competition.

Barring BT would rebalance the country’s spectrum somewhat – BT’s holding would fall from 45 per cent to 42 per cent, according to the regulator.

As part of the same auction, Ofcom will sell 150MHz in the 3.4GHz band. This spectrum is not immediately available to most mobile devices, but will become so in future years. It is earmarked for 5G across Europe.

Because of their lack of immediate availability, BT is free to bid for frequencies in the 3.4GHz band.

Ofcom’s auction, which is slated for next year, will significantly increase the amount of spectrum available to the UK mobile industry. The regulator estimates it will increase by nearly one third. The total amount of mobile spectrum will grow from 647MHz to 837MHz.

The closing date for responses to Ofcom’s proposal is 30 January, 2017.