Washington Redskins tight end Fred Davis was suspended indefinitely without pay on Wednesday for violating the NFL's substance abuse policy.

The suspension begins immediately.

Davis, 28, is set to become a free agent in March. He previously served a four-game suspension for a failed drug test in 2011.

Davis said Wednesday the suspension stems from a supplement he took that contained a banned substance.

"In the past, I made the mistake of knowingly ingesting a banned substance," he said in a statement. "For over two years, I've worked very hard to eliminate marijuana from my life, and I have not had a positive test for it since 2011. Unfortunately, a couple of months ago I took a supplement that contained a banned substance. I now know that supplements are not regulated by the FDA and may contain banned substances.

"The NFL policy is strict, and not knowing that a supplement might contain a banned substance doesn't excuse a violation of the policy. I've worked closely with the NFLPA and NFL to resolve this violation, and I will be permitted to apply for reinstatement in the fall. I look forward to staying in football shape, remaining in compliance with the NFL policy, and having a chance to get back on the field to contribute to a team's success next season."

Davis may have limited options in the NFL. Aside from the off-the-field issues, Davis had just seven catches for 70 yards with a touchdown in 10 games in 2013. He was also slowed by injuries.

Davis, a second-round pick in 2008, has 162 career receptions, with a career high of 59 in 2011.