A top U.S. official says documents that could be helpful in making nuclear weapons have been found in an al-Qaida safe house in Afghanistan. U.S. homeland security director Tom Ridge confirmed the discovery Thursday and also said the U.S. government remains on the highest state of alert for further terrorist attacks.

Mr. Ridge says the nuclear weapons-related information found in Kabul appeared to have been taken off the Internet some years ago. He also says it could have been widely available to people other than the al-Qaida terrorists.

Mr. Ridge says the discovery of the documents is consistent with statements from Osama bin Laden expressing a desire to acquire nuclear weapons.

Meanwhile, the homeland security director says U.S. officials remain on the highest state of alert. Mr. Ridge concedes that the recent military success against the Taleban in Afghanistan raises the risk of future terrorist attacks. "It makes a great deal of common sense to conclude that if you are putting pressure on your enemy in one area or in one venue, they may choose to act out in a separate area or a different venue," he said. "So that is one consideration that obviously is in play. But I think that our state of readiness is as high as it has ever been and will remain that high until we have apprehended bin Laden and dismantled al Qaida."

Members of Congress meanwhile are growing increasingly concerned with the threat of cyber-terrorism, possible attacks on the nation's information infrastructure.

Florida Republican Cliff Stearns chairs a congressional subcommittee that has been monitoring the cyber-terror threat. "If there are concerted attacks yielding substantial breaches of our nation's information systems, not only will we face staggering financial losses, we will also face more instances of tragic loss of lives," Representative Stearns said. "As our information system infrastructure has become interoperable, easy to access and used for the sake of increasing efficiency and productivity, it has become more vulnerable to cyber-attacks."

Computer security experts say it is essential that government and private industry form a partnership to find ways to prevent cyber-terrorism and to shore up the security of computer information systems.

Among those testifying before lawmakers Thursday was Warren Axelrod, director of global information security with the Pershing Company in New Jersey. "We need the ability to pursue cyber-attackers and prosecute them fully if we are to discourage others from attacking our networks and computers," said Mr. Axelrod. "I would propose that Congress consider legislation to further empower law enforcement to track down perpetrators. We also need reciprocal arrangements with friendly countries so that they will support these endeavors."

Before September 11, members of Congress were most concerned with blocking destructive computer viruses that in the past two years have cost businesses an estimated $10 billion.

Now, lawmakers say they are more concerned with protecting the nation's information systems from what they perceive as a growing threat from terrorists.