Questions by team representatives regarding sexual orientation to collegiate players hoping for a multi-million-dollar National Football League career have prompted an investigation by the league.

An NFL statement on its website said the league would look into reports that prospects were asked improper questions at the NFL Scouting Combine, four days of physical tests and interviews that ended Tuesday in Indianapolis.

University of Colorado tight end Nick Kasa first raised the issue in a radio interview with ESPN on Tuesday.

"(Teams) ask you like, 'Do you have a girlfriend?' 'Are you married?' 'Do you like girls?', those kinds of things," Kasa said. "It was just kind of weird, but they would ask you with a straight face."

University of Michigan standout Denard Robinson and Michigan State running back Le'veon Bell made similar claims Thursday in radio interviews, Bell to Detroit station WDFN and Robinson in a syndicated show with Dan Patrick.

The NFL warned that any team asking about the sexual orientation of any player faces punishment from the league.

"Like all employers, our teams are expected to follow applicable federal, state and local employment laws," the league statement said.

"It is league policy to neither consider nor inquire about sexual orientation in the hiring process.

"In addition, there are specific protections in our collective bargaining agreement with the players that prohibit discrimination against any player, including on the basis of sexual orientation.

"We will look into the report on the questioning of Nick Kasa at the scouting combine. Any team or employee that inquires about impermissible subjects or makes an employment decision based on such factors is subject to league discipline."

Among the players at the combine was Manti Te'o, the college star at Notre Dame who told television interviewer Katie Couric that he was not gay in the aftermath of a bizarre situation involving an elaborate hoax and fictional girlfriend.