LOS ANGELES -- NBC and the union that represents television performers are investigating an allegation by an "America's Got Talent" judge that she was fired because she complained of racism and other on-set issues.

The Screen Actors Guild-American Federation of Television and Radio Artists says in a statement Monday that it is investigating the allegations from Gabrielle Union, and that it takes such claims seriously.

A statement Sunday from NBC and the production companies behind the show says they are committed to ensuring a respectful workplace and are talking to Union's representatives about her concerns.

According to reports, Union, who is black, sought action to address an environment she said allowed racist jokes and comments and other troubling behaviour, including judge-producer Simon Cowell's smoking indoors.