Amazon is being sued by the US Federal Trade Commission (FTC) for allegedly allowing millions of dollars of unauthorised purchases by children in its mobile app store.
Amazon has declined a settlement offer and has said that it will not accept tighter controls.
"Amazon's in-app system allowed children to incur unlimited charges on their parents' accounts without permission," said FTC chair Edith Ramirez in a statement. "Even Amazon's own employees recognized the serious problem its process created," she added.