Top U.S. intelligence officials Tuesday appeared before a joint House-Senate committee investigating the September 11 terrorist attacks. The focus of the hearing dealt with how the al-Qaida terrorist network operates.

The directors of the Federal Bureau of Investigation, Central Intelligence Agency and National Security Agency all testified at the closed-door hearing.

During a break in the proceedings, Democratic Senator Bob Graham of Florida, chairman of the Senate Intelligence Committee, told reporters much of the hearing dealt with how al-Qaida operates.

"Al-Qaida takes an average of approximately three years from the time it develops a specific target of attack until it executes it," he said. "In those three years, there is a systematic process of among other things, identifying the people who can carry out the project."

Mr. Graham says lawmakers want to know how al-Qaida terrorists are recruited, trained and financed, as well as how they are organized in a command structure. The hearings will resume Wednesday.

The United States has blamed al-Qaida and its leader, Saudi-born Osama bin Laden, for the September 11 attacks.

The joint Congressional panel is investigating whether U.S. intelligence agencies could have prevented the attacks.

In a related matter, Congress has begun considering President Bush's plan to expand the Office of Homeland Security to a cabinet-level agency.

Homeland Security Director Tom Ridge briefed Congressional leaders Tuesday, and then spoke to reporters about the components of the plan.

"There are four pillars in this piece: the research and development; the weapons of mass destruction countermeasures; the intelligence analysis, integration and infrastructure protection and border security; and the domestic preparedness response," he said.

In a letter to Congress appealing for its support, President Bush said America needs a homeland security establishment that can help prevent catastrophic attacks and mobilize national resources for an enduring conflict while protecting the nation's values and liberties.

For their part, lawmakers pledged to work in a bipartisan manner to pass the legislation quickly. They would like to complete work on the bill and send it to President Bush for his signature before the one-year anniversary of the September 11 attacks.

In what would be the largest reorganization of the federal government in a half century, Mr. Bush wants to include in the new department all or parts of nearly two dozen existing federal agencies. Among them are the Secret Service, Coast Guard, Border Patrol, and the Immigration and Naturalization Service.

The CIA and FBI would not be included, to the disappointment of some lawmakers who argue the new department would not address a problem highlighted by the September 11 attacks - the failure of the two agencies to share intelligence.