BOSTON (AP) Nonprofit groups are calling on the National Football League to stop offering fantasy sports competitions to children.

The National Council on Problem Gambling and the Campaign for a Commercial-Free Childhood say in letters to the league Wednesday that it wrongly marketed fantasy football games to kids on its website, smartphone app and elementary school curriculum.

They believe the games could lead children toward future gambling addictions.

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NFL spokesman Brian McCarthy says parents had to provide consent and could opt out of the prize competition for their children.

The ''NFL Rush Fantasy'' competition was open to children ages 6 to 12 this past season. The weekly prize was an Xbox console and the video game Madden NFL. The grand prize was a four-day trip to Hawaii for the Pro Bowl game.