San Diego Chargers tight end Antonio Gates has been suspended four games without pay four violating the National Football League's substance abuse policy, the team said on Wednesday.

Gates, an eight-time Pro Bowl selection who is considered one of the best tight ends to ever play in the NFL, said he was unaware at the time that the substance he took to help recover from a long season was prohibited.

"As an NFL veteran and team leader, I should have done my due diligence to ensure that what I was taking for recovery was within the NFL guidelines," Gates, 35, said in a statement.

"I have always believed that ignorance is no excuse when it comes to these issues, and I take full responsibility for my actions."

The 12-year veteran, who is eligible to participate in all offseason and preseason practices and games, can return to the Chargers' active roster on Oct. 5, according to the NFL.

Gates had 12 touchdown receptions last season, which was tied with New England's Rob Gronkowski and Denver's Julius Thomas for most by a tight end.

"We are tremendously disappointed for our team and our fans as well as Antonio, but no more disappointed than Antonio is with himself," the Chargers said in a statement.

"We have the utmost confidence he will stay in excellent shape for the season and be ready to go when he returns."

(Reporting by Tim Wharnsby in Toronto; Editing by Frank Pingue)