By Brendan O'Brien

(Reuters) - Chicago Bears great Gale Sayers has filed a federal lawsuit against the National Football League, accusing it of failing to warn him about and protect him against head injuries, including multiple concussions, during his eight-year Hall of Fame career.

The lawsuit, filed in a Chicago federal court on Friday, comes three weeks after the league agreed to pay $765 million to settle a lawsuit brought by thousands of players, many suffering from dementia and health problems, who accused the league of hiding the dangers of brain injuries.

Sayers, 70, suffers from headaches, occasional short-term memory loss and other cognitive deficits as a result of repeated head trauma, including multiple concussions he endured while playing in the NFL, according to the suit.

Sayers accuses the NFL of not warning him that playing through concussions and brain traumas could and would cause permanent brain damage, according to the lawsuit.

He also says the NFL, on numerous occasions, failed to enact sufficient return-to-play policies, allowing and encouraging him after suffering concussions to return to game action or practice.

The lawsuit accuses helmet maker Riddell of failing to warn him of the risks of concussions, and of not disclosing that the helmets would not prevent concussions.

The lawsuit asks Riddell to pay Sayers $50,000 and court costs. It does not specify damages against the NFL.

Sayers, known as the Kansas Comet, played running back for Chicago from 1965 to 1972, when he retired in the preseason. Sayers led the league twice in rushing and was a four-time Pro Bowler during his career that was cut short by knee injuries.

Sayers was inducted into the Pro Football Hall of Fame in 1977.

In 1970 he published a memoir, "I am Third," describing his rise to football glory and his friendship with Chicago Bears teammate Brian Piccolo, who died of cancer. The autobiography was the basis for the 1971 film, "Brian's Song."

(Reporting By Brendan O'Brien; Editing by Karen Brooks and Xavier Briand)