KANSAS CITY, Mo. (AP) -The president of a national gay advocacy group is asking the NFL and the Kansas City Chiefs to take action after running back Larry Johnson used a homosexual slur this week.

Johnson, a two-time Pro Bowl running back for the Chiefs, posted the slur on his Twitter account Sunday in a response to another tweet. On Monday, he said it again in refusing to talk with reporters, according to a recording made by the Kansas City Star.

The president of the Gay & Lesbian Alliance Against Defamation, Jarrett Barrios, says the NFL and Chiefs need to take disciplinary action. Barrios says the word is used to ridicule and harass young gay and transgender athletes.

The Chiefs and the NFL say they are looking into the matter. Chiefs spokesman Bob Moore declined immediate comment Tuesday.