Mobile phone operators have been warned not to derail the upcoming auction of radio waves allowing superfast next generation mobile internet. Rules published by communications watchdog Ofcom have angered some of the network providers, who believe they give an unfair bias to their rivals. O2 is the latest firm to complain, saying the rules could mean two of its rivals could buy 4G spectrum at a steep discount. The firm hinted it may take legal action. Last week the UK’s biggest operator Everything Everywhere raised similar concerns.