U.S. President Joe Biden has rejected several conditions sought by five Guantanamo Bay prisoners as part of a deal with federal prosecutors that would see them plead guilty to conspiring in the Sept. 11, 2001, attacks, the New York Times reported on Wednesday.

The five defendants, including Khalid Sheikh Mohammed, the al Qaeda militant accused by the U.S. of being the principal architect of the attacks, have been offered a plea agreement by prosecutors that would spare them the death penalty in exchange for admitting guilt and a life prison term, the Times reported.

But the defendants have responded with a list conditions, including that they not serve their life sentences in solitary confinement and would be allowed to eat and pray with other inmates, the newspaper said.

The White House confirmed that Biden concurred with Defense Secretary Lloyd Austin's recommendation not to accept the conditions, known as joint policy principles, as a basis for plea talks.

"The 9/11 attacks were the single worst assault on the United States since Pearl Harbor. The president does not believe that accepting the joint policy principles as a basis for a pre-trial agreement would be appropriate in these circumstances," a White House spokesperson said in an email.

"The administration is committed to ensuring that the military commissions process is fair and delivers justice to the victims, survivors, families, and those accused of crimes," he said.

More than 3,000 people were killed in the hijacked plane attacks by al Qaeda militants using four commercial airline jets, flying two of them into the twin towers of the World Trade Center in New York City.

The militants crashed a third plane into the Pentagon in Washington, D.C. The fourth plane went down in rural Pennsylvania after passengers fought back against the hijackers.