Baltimore Ravens star Haloti Ngata has been suspended for four games by the NFL for violating the league's policy on performance-enhancing substances.

The suspension begins with immediate effect and so the Pro Bowl defensive lineman will miss the remainder of the regular season.

"I made a mistake, and I own this," Ngata said in a statement released by the team.

"I took Adderall and take full responsibility for doing this. I am deeply sorry and broken up over this. I let down my family, my teammates, Ravens fans and myself. My hope is that the Ravens make the playoffs, and I believe they can do this. And, then I can come back and help us win."

The 30-year-old's suspension runs through to the team's final regular-season game against the Cleveland Browns on December 29.

However, his absence will be a blow for the Ravens as he ranks eighth in the league in his position serving as the anchor of Baltimore's 3-4 scheme.