A 17-year-old New Yorker has been charged with dragging a young boy to the top of a six-story apartment building and throwing him off, prosecutors said on Friday.

The nine-year-old victim remains on life support in a medically induced coma at a New York hospital after the February 1 incident, the Bronx District attorney's office said in a statement.

Casmine Aska was charged with attempted murder and assault and faces up to 25 years in prison if found guilty.

"Aska grabbed the young child by the legs and dragged him up a flight of stairs to the roof, picked him up and threw him from the roof," the prosecutor's office said.

The boy was being treated for numerous broken bones and severe internal bleeding.