Dozens of the nation's most popular websites for children have been fined for illegally tracking them online.

New York Attorney General Eric Schneiderman says his office studied kid-focused websites for two years. The websites are owned by Viacom, Mattel, Jumpstart and Hasbro.

He says his investigators discovered the sites contained software from third-party advertisers that was tracking children's online behavior. Schneiderman says the activity is in violation of the Federal Children's Online Privacy Protection Act, which prohibits the unauthorized collection of children's personal information online.

"In some cases, the host companies were not even aware until we told them the tracking technology was on their sites," says Schneiderman. "When we notified them, each of them took immediate action."

Schneiderman says the sites removed the tracking software and updated their privacy policies.

Schneiderman says the companies that were investigated were fined a total of $835,000 and have agreed to future inspections by investigators.