The attorney for Phillies first baseman Ryan Howard has threatened to sue cable network Al Jazeera after the station aired a documentary Sunday night that accused Howard of allegedly using performance enhancing drugs to add "some more explosiveness" to his swing.

Howard's attorney William Burck, who works for powerful law firm Quinn Emanuel, called Al Jazeera "inexcusable and irresponsible." Burck also represents Washington Nationals infielder Ryan Zimmerman, who was accused along with Howard in the documentary titled The Dark Side. Major League Baseball said it will conduct a thorough investigation. Howard and Zimmerman both denied the claims.

"The extraordinarily reckless claims made against our clients in this report are completely false and rely on a source who has already recanted his claims," Burck said.

In the report, British hurdler Liam Collins goes undercover in an attempt to expose the use of performance enhancing drugs in professional sports. He meets with pharmacist Charlie Sly, under the guise that Collins is trying to qualify for next summer's Olympics. Sly recanted all of his statements Saturday night and called Collins a "recruited fraudster."

Sly, not knowing that he is being recorded, tells Collins that he supplied Howard with Delta-2, a designer drug banned by Major League Baseball. According to the drug's website, Delta-2 is "steroidal in nature but is not an anabolic androgenic steroid because it is not structurally related to Testosterone."

Sly tells Collins that Delta-2 is "great for strength gains" and is used by a lot of football and baseball players. Sly said the drug, which is injected with a syringe, adds a 10- to 15-percent increase in strength. Sly told Collins that he has had access to the drug since 2006. Collins asked him about working with Howard. Sly said Howard "is somebody that you can not overwhelm with stuff.

"You just make sure you have everything in bags," Sly said in the video. "He knows to take stuff twice a day. Usually, I just have him teach it back to me."