ISTANBUL: A decision by Turkey's competition board to fine banks a record amount for collusion on interest rates was inconsistent and unfair, the banking association said on Saturday.

The board fined a dozen of the country's banks a total of $ 620 million on Friday, the largest penalty it has imposed on the sector.

"The banking sector...has a central role in the economy and is functioning under highly competitive conditions as a result of its structure," the Banks Association of Turkey said in a statement. "The competition board's decision didn't consider this different structure of the sector at all."

The decision was a final verdict of an investigation which began in November 2011. The banks were accused of agreeing maximum deposit rates, interest rate increases on credit cards, and commissions and fees for card services.

"The board decision is far from reflecting the truth, inconsistent and unfair...Therefore it has created a lack of confidence in the sector," the association said.

The board could have imposed fines of up to 10 percent of turnover, although it has never applied a sanction of more than 0.5 percent of turnover in previous such cases.