A Puerto Rican senator who allegedly posted a picture of his naked buttocks on gay iPhone app Grindr says he is the victim of political enemies.

New Progressive Party Senator Roberto Arango, who has not denied the images are of him, has opposed gay marriage, gay couples adopting and equal workplace rights.

In a resignation letter effective today, he said: “I affirm with the utmost certainty that the controversy which Puerto Rico’s Senate and the city capital is currently facing is the result of a sinister maneuver orchestrated by my political enemies.”

Apparently referring to Grindr, he added: “I’ve been a victim of my own ingenuity and of technological advances that, upon falling in the wrong hands, can be transformed into something very harmful.”

One of the images, revealed by Puerto Rican media earlier this week, show a naked man on all fours taking a picture of his bottom in a mirror.

In another, the topless man is wearing a necklace similar to one Mr Arango has been seen wearing.

Earlier this week, the politician told local media: “You know I’ve been losing weight. As I shed that weight, I’ve been taking pictures.

“I don‘t remember taking this particular picture but I’m not gonna say I didn’t take it. I‘d tell you if I remembered taking the picture but I don’t.”