The European Commission yesterday accused mobile firms of charging too much for calls made while people travel abroad and said it would take action to bring down "roaming" tariffs.

From the autumn the commission will begin publishing the tariffs charged by European mobile operators on a special website to increase price transparency.

It will also continue to process separate investigations into the tariffs, which could lead to fines.

Roaming tariffs are the fees that mobile operators charge consumers for making or receiving mobile phone calls while they travel abroad.

The prices of these calls vary greatly depending on which operator consumers use to make or receive a mobile call.

For example a one minute call from Cyprus to Finland made by a subscriber of a Finnish operator would cost 58 cents.

However, a Polish mobile phone subscriber ringing Poland from Malta could pay a rate of €5.01 per minute.

"Using your mobile phone while on holiday can still lead to a very unpleasant surprise," said Viviane Reding, commissioner for information society and media.

"I am convinced that substantially more progress from the industry is both necessary and possible."

The commission has highlighted the high cost of roaming charges for several years and is undertaking at least two investigations that could lead to penalties against operators.

The former competition commissioner Mario Monti said last year that a preliminary enquiry had found that consumers were charged excessive roaming tariffs by Vodafone and O2 when they travelled to Britain.

The findings followed a four year enquiry by the commission and are being opposed by the mobile operators.

A separate enquiry consucted by Ms Reding's department in cooperation with European regulators may seek to impose price caps on roaming charges in the future.