Osama bin Laden threatened Al Qaeda would kill any Americans it takes prisoner if accused Sept 11 mastermind Khalid Sheikh Mohammed is put to death, according to an audiotape aired on Al Jazeera on Thursday.

Senior US officials may recommend that Mohammed, who was being held at the US military prison at Guantanamo Bay, Cuba, be prosecuted in a military trial, officials said in March.

Such a decision, after intense political pressure, would reverse plans to hold criminal trials for Mohammed and four accused co-conspirators in a lower Manhattan court.

"This message is about our prisoners who you are holding," bin Laden said in the tape, complaining that US President Barack Obama was still following "his predecessor's steps" on many issues including on Al Qaeda detainees such as Mohammed.   

"The White House has expressed its desire to execute him. When America makes this decision, it will have made a decision to execute whoever of you is held prisoner by us," bin Laden said in the recording.

There was no immediate comment from Washington.        

Mohammed has claimed responsibility for organising the Sept 11, 2001, attacks on the United States and bombs in Indonesia, Kenya and elsewhere, and if convicted of murder, conspiracy, terrorism and other charges, could face the death penalty.

"It is fair to treat each other the same. War is a back-and-forth," bin Laden said. "The White House politicians were and still are oppressing us, particularly in providing support to the Israelis and occupying our land in Palestine. They were thinking that America was safe behind oceans from the anger of the oppressed until the reaction was strong in your house on the 11th."    

When Obama took office in January 2009, he set a one-year deadline to close the Guantanamo facility but political and diplomatic complications have forced a delay.

The administration plans to prosecute almost three dozen terrorism suspects held at Guantanamo Bay but has not announced where all the trials will be held and whether they will be criminal or military. - Reuters