Washington D.C., Sept. 18 -- : Backstreet Boys singer Nick Carter has filed a restraining order against his brother Aaron Carter saying that he threatened to kill his "pregnant wife and unborn child."

"After careful consideration, my sister Angel and I regret that we were required to seek a restraining order against our brother Aaron today," Nick, wrote in a tweet on Tuesday.

"In light of Aaron's increasingly alarming behaviour and his recent confession that he harbours thoughts and intentions of killing my pregnant wife and unborn child, we were left with no choice but to take every measure possible to protect ourselves and our family," Nick said.

Continuing further the singer wrote, "We love our brother and truly hope he gets the prope...