British holidaymakers will lose out on cheap calls from abroad this summer because mobile operators are dragging their feet over new European Commission laws on the use of phones abroad.

Orange, T-Mobile and 3, the British mobile operators, are all insisting that their customers will benefit from a new, cheap “Eurotariff” for roaming only from the legal deadline of August 30 - too late for most people’s summer breaks.

In stark contrast, operators elsewhere in Europe - including T-Mobile itself in Germany - have already made the new tariff available to their customers in these markets.

This week the Commission will launch a special website naming and shaming tardy operators, such as the three British offenders. It will high-light those mobile companies who have entered into the “spirit” of the new roaming laws, rather than just the letter, and rushed to enable customers to benefit from cheaper tariffs ahead of the legal deadlines that it has laid out. Brussels estimates that about half of mobile companies in the European Union have already activated the Eurotariff.

Viviane Reding, the European Commissioner for Information Society and Media, announced plans last year to introduce new legislation to cut the cost of making calls from abroad.

The move – which drew fierce opposition from many mobile companies – followed evidence that holidaymakers were being charged unfairly high prices for phoning home when on holiday. Calls made from abroad were up to 50 times more expensive than a standard UK national call. Under the new Eurotariff, the cost of making a roaming call will be capped at 49 euro cents (33p) a minute and an incoming call at 24 cents (16p) a minute, exclusive of VAT – a cut of up to 70 per cent on existing charges. The price caps are to be lowered in 2008 and 2009.

In their attempted defence, mobile operators such as 3 are likely to point out that they are cutting their prices below the level required by the EU laws.

Mobile phone companies must have informed their customers about the new tariff – either by letter or text message – by today at the latest. The user must be able to benefit from the tariff from within one month of responding to the letter, with a backstop deadline of August 30. Other customers will be automatically transferred by the end of September.

Operators who miss either today’s deadline or the other deadlines risk sanctions including a fine of up to 10 per cent of their revenues. Britain’s biggest mobile operator is expected to opt out of the broadband price war by shunning “free” broadband when it launches this autumn. Peter Erskine, chief executive of O2 , said that consumers were wary about offers of “free” broadband, which are marketed by a slew of big-name players. He also said that the mobile group was weighing up launching a fixed-line service with its broadband.