MIAMI (Reuters) - They're big, they're tough, and, presumably, some of them are gay, but so far not a single active NFL player has come out and said so. After NBA player Jason Collins broke that barrier this week, the National Football League is making sure it will be ready for any coming out party.

Earlier this year, at least three college football players said they had been asked about their sexual orientation during NFL recruitment interviews, sparking calls for the NFL to do more to fight discrimination.

Just hours before Collins' coming out statement was published by Sports Illustrated on Tuesday, the NFL - America's most popular sport, with $9 billion a year in revenue - released a ‘workplace conduct statement' regarding sexual orientation.

"The NFL has a long history of valuing diversity and inclusion. Discrimination and harassment based on sexual orientation is not consistent with our values and is unacceptable in the National Football League," league commissioner Roger Goodell says in the document.

League spokesman Greg Aiello told Reuters that the timing of the release was purely coincidental and that the document had been worked on for several weeks with no advance notice given to the NFL about Collins's impending statement.

The memo, sent to chief executives, club presidents, head coaches and general managers, highlights a tough policy on reporting acts of discrimination or harassment and makes clear that questions about sexuality are not permitted during recruitment interviews.

Collins' statement, and the reaction to it, has raised expectations that other gay athletes will feel the time is right to come out. Leading players in the NBA, including LeBron James and Kobe Bryant and top coaches such as Boston Celtics' Doc Rivers, expressed support for Collins.

Several reports have indicated that one or more NFL players may be close to coming out.

Earlier this month, Brendon Ayanbadejo, who played in the Super Bowl-winning Baltimore Ravens team last season, said up to four players were considering jointly revealing their sexuality.