Australia"s competition watchdog has admitted international roaming costs for mobile phones are too high.

While business travellers are well aware of the high costs, it is the first time the Australian Competition and Consumer Commission (ACCC) has expressed concern.

International roaming allows consumers to temporarily connect to a mobile phone network within the country they are visiting.

For this service to be provided, the mobile phone service provider to an Australian user must have a "roaming" deal with the foreign operator.

"The ACCC"s final report expresses concerns that prices for international roaming services appear to be very high - especially as compared to charges set for other mobile telephone services," ACCC commissioner Ed Willett said in a statement.

The most significant factor in the setting of retail prices paid by Australian travellers for roaming services was the wholesale price set by foreign operators when consumers roam on their networks.

The ACCC said it did not have the power to regulate these wholesale charges.

However, competition in the retail market for international roaming services appeared to be improving, with greater availability of substitute services such as prepaid international calling cards, SIM cards and mobile phone rentals.