The ACCC has issued a statement regarding the charges associated with mobile data usage. Released yesterday, the statement warns that customers with 3G mobile phones can face high fees once they exceed their monthly data allowance.

The statement comes after the recent release of the iPhone 3G in Australia and the steady rise in mobile data use.

"The ACCC is particularly concerned that consumers may be misled if they are not made sufficiently aware that their data allocations can be exceeded — at significant cost", said ACCC chairman Graeme Samuel.

"In the case of smartphones, consumers can download greater amounts of information from the Internet than ever before. With this, comes the potential for them to exceed their phone plan value and incur considerable additional charges."

Excess data usage charges vary between telcos. However, they can reach as high as $1 per MB when a customer exceeds his or her monthly data allowance. Telstra is currently the most expensive carrier for excess usage charges, at $1 per MB on its current iPhone 3G plans. It also offers separate data allowance plans at $59 per month that incur a cheaper excess usage fee of 25c per MB. Optus currently charges 35c per MB for excess data on its iPhone 3G plans; Vodafone is the cheapest at 12c per MB.

Although other smartphones are equally capable for Web browsing, the iPhone 3G has sparked the warning due to its relative popularity and the higher proportion of its owners who use its Web browser over both Wi-Fi and 3G bandwidth compared to owners of other mobile phones.

"Earlier this month the ACCC wrote to telecommunication carriers alerting them to concerns about the potential for consumers to be misled about mobile data usage charges", Samuel said.

It appears that some carriers are already reacting. Yesterday, Optus revealed its new 'Timeless' plans, with 2GB of data allowance included in the $129 cap, and an excess usage charge of 35c per extra MB.

As yet, the ACCC has not confirmed whether it will be taking any further steps in regards to the issue.

For more information on iPhone plans, you can check out our rundown of individual plans from telcos. You can also check our investigation into international roaming data charges for the iPhone 3G.