WASHINGTON – A senior lieutenant to Osama bin Laden has told American interrogators that the Al Qaeda leader’s big mouth was a security liability.

Khalid Sheikh Mohammed also complained that the schemes bin Laden approved lacked destructive ambition. Court papers depict the notorious terrorist group riven by internal disputes and hobbled by favoritism.

The allegations have emerged from CIA interrogations of Mr. Mohammed, the Kuwaiti accused of masterminding the September 11 conspiracy. His comments were released as part of the evidence in the trial of the would-be suicide pilot Zacarias Moussaoui.

Mr. Mohammed, held in American custody at an unknown location since his capture in Pakistan three years ago, portrays himself as a brilliant terrorist manager. Throughout the discussion, he is almost contemptuous of Mr. bin Laden, who held the purse strings.

According to Mr. Mohammed, Mr. bin Laden lacked inspiration and vision. The Saudi failed to understand the basic security requirements of terrorist plots, such as keeping silent about impending attacks. Mr. Mohammed cites Mr. bin Laden’s decision to inform a group of visitors to his Afghan headquarters that he was about to launch a major attack on American interests.

Then he told trainee terrorists at the al-Farooq training camp “to pray for the success of a major operation involving 20 martyrs.”

Mr. Mohammed and a fellow terrorist manager, Mohammed Atef, who was later killed in an American air attack, were so concerned that they asked Mr. bin Laden to shut up.

The men “were concerned about this lack of discretion and urged bin Laden not to make additional comments about the plot.” Mr. Mohammed has been credited with inventing the use of hijacked aircraft flown into buildings as a terror method. His review of the first World Trade Center attack in 1993 convinced him that even the biggest truck bombs lacked destructive impact.

When he tried to convince Mr. bin Laden that they should hijack 10 passenger aircraft and crash them into American “targets” in 1996, the Saudi was dismissive.

Three years later, a less ambitious hijacking plot was approved by Mr. bin Laden. But he then caused endless problems by insisting on picking the suicide crews himself.

Although Mr. Mohammed’s statements are the result of interrogation, his words tally with counter-terrorism experts’ understanding of his relationship with Mr. bin Laden. A former FBI agent said, “They couldn’t stand each other. They both had huge egos.”

Mr. Mohammed also said he had profound doubts about Moussaoui, another of Mr. bin Laden’s favorites, who was judged eligible for execution by an American jury this week.

Believing that Moussaoui was not a “suitable operative,” Mr. Mohammed sought to have him expelled. Mr. bin Laden intervened, sending Moussaoui for a terrorist refresher course and declaring him “reformed.”