OFCOM is to investigate the high rates charged by mobile phone companies to customers who use their phones abroad.

The inquiry, which will begin next month, comes amid mounting concern that holidaymakers are being “ripped off” by extortionate roaming rates. Research by Ofcom has shown that callers who use their phones within Britain enjoy some of the cheapest tariffs of any country. However, calls made to the UK while abroad can be up to 75 times more expensive than a standard UK national call.

For example, an O2 user in the UK can pay only 2p a minute, whereas a call to the UK from France on a pre-pay phone can be as much as £1.49 a minute.

The Ofcom investigation, which will include consultation with mobile operators and industry bodies, is expected to look at both the amounts that UK operators such as Vodafone, Orange, O2 and T-Mobile charge foreigners for using their phones in the UK and the sums that Britons abroad pay for using their phones.

Vodafone and O2 are already under investigation by EU officials for the amounts that they charge foreigners for using their mobiles in the UK.

The European Commission has accused the two groups of charging “unfair and excessive” prices to continental companies for roaming agreements.

The Ofcom inquiry is likely to focus not just on call prices, but also on the charges that mobile phone companies apply to holidaymakers for picking up voice messages and for texting their friends and families back home.

T-Mobile, the German-owned mobile company, charges Britons in France, Spain and Germany 75p per minute for picking up answer phone messages and 40p for every text message they send. In Turkey, a non-EU country, the costs with T-Mobile rise to £1.40 a minute for a call or for listening to voice messages.

Mobile operators claim that calls abroad are more expensive because of fees levied on operators by foreign companies for using their networks and due to currency fluctuations.

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