WASHINGTON -- Eyewitnesses, lawmakers and relatives of victims are among those invited to speak at the first public hearing of the independent commission on the Sept. 11 terrorist attacks.

The hearing will mark the first public action of the 10-member National Commission on Terrorist Attacks Upon the United States. The commission has held four meetings so far, most recently on Thursday, but all have been private.

"It will allow people who have a stake in finding out what happened, who were affected very deeply by the events of Sept. 11, to state what they hope the commission achieves," the panel's spokesman, Al Felzenberg, said Friday.

The hearing will be held March 31 and April 1 at the former U.S. Customs House in New York City, half a mile from the remains of the World Trade Center.

Congress and the White House created the panel last year to explore the causes of the Sept. 11 attacks, preparations for future terrorism and the response to the airline hijackings that killed thousands at the World Trade Center, the Pentagon and in southwestern Pennsylvania.

The commission's broad list of study topics includes intelligence, law enforcement, diplomacy, immigration, aviation and the flow of assets to terrorist organizations. Its report is due in May 2004.

Commission leaders agreed early on that they need much more than the $3 million budget approved by Congress. Felzenberg confirmed that the commission is seeking $12 million to $15 million. A request for more money could be part of a supplemental budget proposal that President Bush will send to Congress to cover the war in Iraq.