WASHINGTON — Osama bin Laden has threatened that al-Qaida will kill U.S. captives if the United States executes self-avowed Sept. 11 mastermind Khalid Sheik Mohammed or other members of the terrorist network in U.S. custody.

The newly released message, which aired on the al-Jazeera network Thursday, comes as officials in Washington are wrestling with how prosecutions of those detainees should proceed. Bin Laden refers broadly to “the captives you have taken from us” in the 74-second recording, but he specifically mentions only Mohammed, who U.S. officials have said could face the death penalty for his alleged role as the principal plotter of the Sept. 11, 2001, attacks.

“The White House has expressed its desire to execute him,” bin Laden said, according to a translation provided by Flashpoint Partners, headed by terrorism expert Evan Kohlmann. “The day America makes that decision will be the day it has issued a death sentence for any one of you that is taken captive.”

U.S. officials dismissed the threat, saying that it has long been clear that Americans captured by al-Qaida cannot expect to live.

“It’s the height of absurdity for anyone associated with al-Qaida to even suggest that – now, at long last – they’re going to start treating captives badly,” said a U.S. counterterrorism official who spoke on the condition of anonymity. “They may have forgotten Danny Pearl and all the others they’ve slaughtered, but we haven’t.”

Pearl, a reporter for the Wall Street Journal, was killed by al-Qaida-linked militants in Pakistan in 2002. After his capture, Mohammed claimed that he had beheaded Pearl “with my blessed right hand.”

Al-Qaida is not believed to have any U.S.-born prisoners. But a Taliban group with close ties to al-Qaida has been holding a U.S. soldier in Pakistan. Pfc. Bowe Bergdahl was captured near a U.S. military compound in Afghanistan in June.

Mohammed previously expressed his desire to be executed in U.S. custody and die as a martyr. He is among five alleged co-conspirators in the Sept. 11 plot being held at the U.S. military prison at Guantanamo Bay, Cuba. The White House recently signaled that Mohammed’s trial will likely take place before a military tribunal.