Describing himself as "a proud gay man," Puerto Rican featherweight Orlando Cruz on Thursday became what is believed to be the first pro boxer to come out as openly homosexual while still competing.

Cruz told The Associated Press in an interview that he is happy and relieved about his decision but had some initial reservations.

"I developed physically and mentally to take such a big step in my life and in my profession, which is boxing, knowing that it would have pros and cons, highs and lows in this sport that is so macho," he said. "I kept this hidden for many, many years."

His announcement comes two weeks before the 31-year-old southpaw challenges Mexican boxer Jorge Pazos for the WBO Latino title. Cruz is currently ranked as the World Boxing Organisation's No.4 featherweight fighter and is 18-2-1 with nine knockouts.

Cruz said he met with psychologists and other people before making the announcement, adding that he has the full support of his family, trainer and manager. He praised his mother and sister for their unconditional love and said his father has always supported him 100 per cent.

"Like every father, he wants his son to be a full-blooded man," Cruz said. "But he is aware of my preference, my taste."

The only other professional boxer who was quoted as saying that he had relations with men and women was US Virgin Islander Emile Griffith, who told The New York Times in a 2005 interview that he struggled with his sexuality. His comments came decades after he ended his 18-year career as a pro boxer.

Griffith is best known for his March 1962 fight against Cuban Benny Paret, who taunted Griffith with gay slurs before the bout. Griffith knocked him out, and Paret died 10 days later.

Cruz said he is prepared for the fallout from his announcement, saying that many boxers had already suspected he was gay but gave him privacy.

"I've been fighting for more than 24 years and as I continue my ascendant career, I want to be true to myself," he said. "I have always been and always will be a proud gay man."

Reaction to Cruz's announcement was largely positive across social media, with many praising him for taking what they called a brave step given the sport's violent history.

Among those who sent messages of support was Puerto Rican singer Ricky Martin, who announced he was gay in March 2010.