WASHINGTON — Federal regulators announced Thursday that they have filed a lawsuit against Amazon.com for allegedly making it too easy for children to make purchases when using mobile apps without a parent’s permission.

The Federal Trade Commission said Amazon charged parents millions of dollars in unauthorized payments for what’s known as “in-app purchases,” typically make-believe items offered within mobile games such as Candy Crush Saga that allow a user to advance to higher levels.

The FTC is seeking refunds for families affected by the unauthorized charges, which began in 2011. It also wants the court to permanently ban Amazon from charging parents for in-app purchases without their consent.

Amazon, whose chief executive Jeffrey Bezos owns The Washington Post, declined to comment. But a spokeswoman cited a letter Amazon sent to FTC Chairwoman Edith Ramirez, saying the agency’s decision to file suit was “deeply disappointing” and that the firm has improved its controls since the Amazon app store was launched in 2011.

The FTC alleges that Amazon violated the FTC Act by billing parents for charges incurred by their children without permission. Amazon’s Kindle Fire tablet was used by children to play games and spend “unlimited amounts of money” to pay for virtual items within the apps such as “coins,” “stars,” and “acorns” without parental involvement. The FTC said that when the app store launched, no password requirements were put in place to stop children from making the purchases.

Just a month after apps were introduced into Amazon’s store, internal emails between staff showed the company was concerned about in-app purchases being made without password protection.

It was “clearly causing problems for a large percentage of our customers,” an Amazon employee said in one email cited in the FTC’s suit. The situation, according to the Amazon email, was a “near house on fire.” The FTC said thousands of parents complained to Amazon about charges made by kids with in-app purchases.

The company changed its policy in 2012, requiring passwords for purchases of more than $20.

Complaints, however, still piled up, the FTC suit says.