British-born American actor Wentworth Miller, who came out as gay in a letter sent to the St Petersburg International Film Festival last month, has revealed that he attempted suicide at 15 by swallowing a “bottle of pills” because he was gay.

At a Human Rights Campaign dinner in Seattle on Monday, Miller spoke to an audience on coming to terms with his sexuality young teenager.

He said: “Growing up I was a target. Speaking the right way, standing the right way, holding your wrist the right way.

“Every day was a test and there was a thousand ways to fail. A thousand ways to portray yourself to not live up to someone else’s standards of what was accepted.”

He added: “The first time I tried to kill myself I was 15. I waited until my family went away for the weekend and I was alone in the house and I swallowed a bottle of pills.

“I don’t remember what happened over the next couple of days, but I’m pretty sure come Monday morning I was on the bus back to school pretending everything was fine.”

Miller also discussed remaining in the closet at the height of his career.

He said: “When I thought about the possibility of coming out might impact me and the career that I had worked so hard for I was filled with fear.”

Miller came out in an open letter to the St Petersburg International Film Festival.

In the letter, he wrote: “I am deeply troubled by the current attitude toward and treatment of gay men and women by the Russian government. The situation is in no way acceptable, and I cannot in good conscience participate in a celebratory occasion hosted by a country where people like myself are being systematically denied their basic right to live and love openly.”

Wilson Cruz, from US LGBT advocacy group GLAAD commended the actor’s decision, saying: “Wentworth’s bold show of support sends a powerful message to LGBT Russians, who are facing extreme violence and persecution: you are not alone. As people from across the globe continue to speak out against Russia’s horrific law, more celebrities and corporations should follow his courageous lead in openly condemning Russia’s anti-LGBT law.”