The European Competition Commission has indicated that it could tell mobile phone operators to lower their charges.
The Commission may cap the price that the companies charge each other when connecting calls from different networks.
The operators have set termination fees that they charge each other for re-routing calls and making calls made from fixed landlines.
In a letter to telecoms watchdog Oftel and the four UK networks, the Commission described the charges as too high and not subject to enough competition.
The letter is an interim statement only as the Commission is not due to issue its final report until January 2003.
Last August, Oftel proposed a price cap on termination fees of the rate of inflation minus 12 per cent, which would save customers an estimated £800m over four years. But the operators rejected the suggestion.
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