U.S. military spokeswoman Lt. Cindy Moore, reacting to the claim, said: "We hope he is not in harm's way. We are making every effort to locate him."
The purported spokesman, Mullah Latif Hakimi, said previously that the Taliban are holding the commando, who has been missing in Afghanistan for 10 days. Hakimi frequently contacts news agencies claiming to speak for the rebels, but his information in the past has proven exaggerated or untrue, and his exact tie to the Taliban leadership cannot be independently verified.
"This American will never be forgiven. Definitely he will be killed," Hakimi said. He said the group would release a video after the man's death.
Hakimi said he was last in contact Wednesday with the rebels who he says are holding the American and was told that his health was good and that he had not been abused. He said the rebels were holding the U.S. service member in a house in Kunar.
The man is the last of a four-member U.S. Navy SEAL commando team missing since last month. One of the men; two others were
A special forces helicopter carrying reinforcements to the area crashed on June 28, killing all 16 Americans on board, the deadliest single attack on the U.S. military since the war here began in 2001.
About 300 troops and several aircraft are in the mountainous area searching for the service member and hunting militants, U.S. military spokesman Col. James Yonts said Wednesday.