Following similar actions taken against Apple and Google, the Federal Trade Commission (FTC) filed a lawsuit against Amazon.com for not taking the appropriate steps to make it more difficult for children to make purchases through its app store without the consent of their parents.

The agency had proposed a settlement that would have compelled Amazon to make restitution for the purchases and to change the app store so that children, who typically buy the apps from their parents' mobile devices, cannot make unintentional purchases.

But the online giant pushed back and the FTC filed suit, saying that the company needs to require passwords for in-app purchases — from which the agency says Amazon makes millions of dollars, simplify the refund process and pump up the visibility of notices warning of the purchases.

Apple refunded $32.5 million to settle a similar complaint.