The Minnesota Vikings have insisted that running back Adrian Peterson will either retire or play for them this season.

The 30-year-old hasn't played since the first game of last season after he was investigated for causing reckless or negligent injury to a child, but has been reinstated ahead of the new campaign.

However, Peterson has not attended any of the voluntary off-season workouts and is said to be upset with a perceived lack of support from the Vikings over the last year.

Head coach Mike Zimmer told reporters: "He's really got two choices. He can either play for us or he cannot play. He's not going to play for anybody else and that's just the way it's going to be."

Peterson has played for the Vikings since 2007.