President Bush and Vice-President Dick Cheney answer questions Thursday from the 10 members of the commission investigating the September 11, 2001 terrorist attack on the United States. The session will take place behind closed doors at the White House.

The president says he looks forward to sitting down with the commission members. "It will be a good opportunity for these people to help write a report that, hopefully, will help future presidents deal with terrorist threats to the country," he said.

White House officials stress it will be a private meeting, not a public hearing.

Presidential spokesman Scott McClellan says it is highly unusual for a sitting president of the United States to take part in a session like this with an investigatory commission established by Congress.

"We want the commission to be able to provide as complete a picture as possible to the American people. And the president has been looking over some materials and documents from the time period leading up to September 11 and right around September 11," he said.

Mr. McClellan says although it will be a joint appearance with Vice President Cheney, the president will answer most of the questions. He says in addition to reviewing paperwork, Mr. Bush has been talking to certain top members of his staff in order to refresh his memory. They include National Security Adviser Condoleezza Rice, Chief of Staff Andrew Card, and White House counsel Alberto Gonzalez.

Mr. Gonzalez will attend the session, and one of his aides will serve as an official note-taker. The meeting will not be recorded and there will be no official transcript, only the detailed notes compiled by staffers from the White House and one from the commission.

Aides to the president say they imposed the ground rules in part because classified information will be discussed. They say the commission agreed, and stress this is not an adversarial process.

The commission has already compiled thousands of documents and heard from numerous witnesses. Scott McClellan says the meeting with the president is coming as the commission nears the end of its work, and begins drafting its final report.

"The president wants to do his part to help them piece together all this information they have so that they can provide the American people with as complete a report as possible and provide the American people with recommendations that might help us do better in winning the war on terrorism," he said.

The White House is likely to provide primarily logistical information on the meeting and little, if anything, on the substance discussed. Commission leaders put out a statement after their earlier private session with former President Bill Clinton, and may do the same after their discussions with Mr. Bush.