Communications regulator Ofcom has announced it has been forced to delay the start of its auction for another chunk of 4G spectrum over proposed legal action from Telefonica and Hutchison, the parent companies of O2 and Three respectively.
Both mobile providers are currently awaiting a decision from the European Commission over a proposed merger, with Ofcom already casting doubt on whether it will win regulatory approval.
The Competition Markets Authority has already given the green light for a merger between BT and EE.
Hutchison and Telefonica have since sent letters to the watchdog stating they will consider taking legal action if the latest auction of 4G spectrum, which was once used by the Ministry of Defence, is allowed to go ahead before the outcome of the European Commission's findings.
Ofcom had been due to start accepting applications from potential buyers this month ahead of a February or March auction.
But the auction could now be delayed until at least the summer, with the European Commission not expected to come up with a verdict on the merger before then.
Ofcom has since said: "After careful consideration, given these specific circumstances, we have decided for reasons of good public administration to delay commencing the auction process."
Matthew Howett, an analyst with research company Ovum, was quoted by the BBC as saying that the impact on consumers would be minimal.
"Despite demand for mobile data growing, all mobile operators are fairly well served by their current spectrum holdings and will be for the short to medium term, so while a delay is unfortunate, it shouldn't be too problematic," he said.