Speaking to Germany's Berliner Zeitung newspaper, European Commissioner for Information Society Viviane Reding said the commission will take action within the next year if roaming prices remain at high levels.
"Using your mobile phone while on holiday abroad can still lead to very unpleasant surprises," warned Reding Monday. "I am convinced that substantially more progress from the industry is both necessary and possible."
A recent study by the commission concludes that mobile phone prices differ greatly between the EU's member states. A Pole calling home from Malta pays almost 10 times more than a Latvian making a similar call from Italy.
The first measure to reduce roaming charges will be to set up a European Web site that compares mobile phone prices. If greater transparency does not reduce the costs, the commission is ready to propose EU regulation in 2006.