Astros prospect Jonathan Singleton has been suspended 50 games for violating Minor League Baseball's drug policy.

A message left Wednesday for Astros general manager Jeff Luhnow wasn't immediately returned, and the Astros have yet to comment about Singleton's suspension, which will start during the 2013 season.

"I was informed today that I have tested positive for marijuana," Singleton said in a statement. "As a result, I am being suspended for the first 50 games of the 2013 season. I accept the penalty and take full responsibility for my actions. I apologize to my parents, the Houston Astros and Jeff Luhnow.

"The Astros have been nothing but supportive of me and good to me in my short time with the organization. My hope is to use this as a learning experience and spend the rest of my career proving to myself and the baseball community that this was a lapse in judgment, and is not in any way indicative of my character or my dedication to baseball or to my team."

Singleton, 21, hit .284 with 21 home runs and 79 RBIs last season for Class AA Corpus Christi. He was expected to attend spring training with the Astros and compete for a spot on the 40-man roster at first base.

Along with prospects such as Carlos Correa, George Springer and Jarred Cosart, Singleton represents a young group of players the rebuilding Astros are heavily counting on as they attempt to improve on back-to-back seasons featuring a combined 213 defeats.