Image caption The regulator has alleged that Visa's practices hurt both customers and retailers

Australia's competition watchdog has sued credit card company Visa for alleged "misuse of market power".

It has accused Visa of preventing customers from using a currency of their choice in transactions.

The regulator also alleged that Visa "engaged in exclusive dealing" and barred retailers from using rival currency conversion services.

The Australian Competition and Consumer Commission alleged that such practices were meant to boost Visa's revenue.

Rod Sims, chairman of the Australian Competition and Consumer Commission (ACCC) said that such moves meant that travellers to Australia were not able to decide "who does their currency conversion when withdrawing cash from an ATM".

"In particular, they are denied the ability to know the cost of transactions in their own currency at the time the transaction is made."

He added that Visa's practices of not allowing use of rival currency conversion systems at merchant outlets also meant that retailers were denied opportunity to share the revenue arising from such transactions.

"Finally, it is alleged that Australian suppliers of dynamic currency conversion (DCC) services were, and continue to be, denied the opportunity to compete with Visa in relation to DCC services at ATMs."