Updated

By Scott Malone

BOSTON (Reuters) - Thirty players in the National Hockey League have joined a campaign intended to promote gay and lesbian equality in sports with a television ad that will premiere during Sunday's matchup of the New York Rangers and Boston Bruins.

The campaign, called "You Can Play," aims to combat what its organizers call an atmosphere of "casual homophobia" in locker rooms, in which slurs are carelessly used, creating a difficult atmosphere for gay, lesbian, bisexual and transgender athletes.

"You've got this thing where people don't think there are, or choose not to believe there are, gay athletes in their locker rooms," said Patrick Burke, a talent scout for the Philadelphia Flyers who is one of the co-founders of the program.

Burke said he hoped the campaign could help to persuade closeted pro athletes to identify themselves publicly, so that they can serve as role models for school-age gay and lesbian athletes.

At the moment, there are no players in the four major U.S. sports leagues -- which also include the National Football League, Major League Baseball and National Basketball Association -- who have publicly identified themselves as gay, organizers said.

"You get what we call casual homophobia, with people almost always not realizing the effect it has on the kid in the corner of the locker room who is gay and is trying to keep it a secret," said Burke.

The campaign consists of a series of video clips initially starring 30 professional hockey players, with the athletes telling the camera "if you can play, you can play" -- meaning they are concerned with their teammates skill on the ice, not their sexual orientation.

It has echoes of the national "It Gets Better" Campaign, launched in 2010 by syndicated columnist Dan Savage in response to a number of suicides by teenagers who were bullied because of their sexuality.

But "You Can Play" focuses solely on acceptance of gay athletes in sports, said Burke, whose brother Brendan, a manager of the Miami University ice hockey team, came out as gay in 2009 and died a year later in a car accident.

The Burke family is closely tied to professional hockey, with Patrick and Brendan's father Brian Burke the general manager of the Toronto Maple Leafs.

While the "You Can Play" campaign starts with NHL players, Burke aims to recruit athletes from other professional and college leagues.

"If you're a young gay hockey player who doesn't have a role model in the adult world, that's a lot harder than if you can look up and say, 'That guy is gay and he did it.' That puts things into a whole new light."

The ads were produced by premium cable TV network HBO, a unit of Time Warner Inc , and will first air on NBC television, owned Comcast Corp and General Electric Co .

(Reporting By Scott Malone; Editing by Paul Thomasch)