Mobile phone companies that do not allow customers to choose a new European Union plan limiting the coast of call from abroad risk legal action and fines as of Tuesday, the European Commission warned Monday.

The new regulations will provide a price cap on roaming fees later this summer, but phone companies first had to offer customers the choice of staying with existing fees or shifting to the new euro-tariff that promises price cuts of up to 70 percent.

"If a customer hasn't received the euro-tariff by today ... he can go to a national court," EU spokesman Martin Selmayr said.

"All roaming customers in the European Union have to be given the opportunity by July 30 to opt deliberately for the new euro-tariff," he said. Companies that fail to offer the option will be "in breach of the regulation."

National telecom regulators could also impose fines on companies that have not obeyed the July 30 deadline.

The EU executive plans this week to post on a website details of which mobile phone companies are in compliance, he said.

The website will explain whether mobile phone firms have offered a price plan at or below the EU cap of euro0.49 (66 U.S. cents) per minute for making a call when abroad, and euro0.24 (33 cents) per minute for receiving one, plus value-added tax.

The EU price ceilings would drop further by 2009 - to euro0.43 (59 cents) for making calls abroad and euro0.19 (26 cents) for receiving them. The regulation would then lapse, unless the EU extends it.