Four Australian banks had approached the company in July with the hope of gaining access to the NFC chips that are a part of all iPhones and enable users to wirelessly pay for things via Apple Pay.

But Apple (AAPL) is arguing that if the four banks—the Commonwealth Bank of Australia, National Australia Bank, Westpac, and Bendigo and Adelaide Bank—use the NFC chips independently of Apple Pay, it would compromise the phones’ security.

“Providing simple access to the NFC antenna by banking applications would fundamentally diminish the high level of security Apple aims to have on our devices,” the company said in a submission to the Australian Competition and Consumer Commission (ACCC).

If the banks’ apps were to use iPhones’ wireless payment system, they would get a cut of the fees that Apple charges when consumers use Apple Pay. Apple’s response comes after the banks worked with the ACCC to negotiate with the company collectively, forming what Apple called a “cartel.”

In its response, Apple said the main motive of the four banks to use the iPhone’s technology is to preserve their credit card businesses. Australian credit card interest rates are usually around 20%, The Register reports, despite home lending rates currently being below 5%.

Fortune reached out the banks and will update the story if they respond.