MIAMI – The NFL Players Association (NFLPA) has filed a lawsuit challenging the suspensions of three New Orleans Saints and two Minnesota Vikings players for breach of the league's steroids policy.

Charles Grant, Will Smith and Deuce McAllister of New Orleans and Kevin Williams and Pat Williams of Minnesota were all suspended by the league on Tuesday for four games.

The lawsuit, filed with the Federal District Court in Minneapolis, asks for an "immediate injunction" to allow the players to take part in this weekend's games.

Bryan Pittman of Houston was also suspended but his case was not mentioned in the statement by the Players Association.

The players were suspended after the NFL ruled they had taken banned substances which could act as masking agents for steroids.

The NFL statement referred to a weight loss product called StarCaps and the league said it had warned teams in 2006 that Balanced Health Products, the makers of StarCaps, had been added to the list of prohibited dietary supplement companies.

However, the NFLPA's lawsuit claims the league failed to notify the players that StarCaps contained a substance that was prohibited by the league's anti-doping policy.

Richard Berthelsen, acting executive director and general counsel of the NFLPA, stated: "We are taking these steps today in hopes of keeping these players on the playing field.

"We strongly believe that the doctors and the NFL should have told us and the players what they knew about StarCaps, but for some unknown reason they failed to meet that duty," added the statement.

The suspensions are a big blow for the Minnesota Vikings, who lead the NFC North. Kevin and Pat Williams, who are not related, are the heart of the team's defense as starting defensive tackles.

The Vikings lead Chicago by a game with just four games remaining in the regular season.