Civil liberties and human rights groups are demanding that the Bush Administration release information about the nearly 1,000 people arrested or detained, in the aftermath of the September 11 terrorist attacks.

Groups ranging from the American Civil Liberties Union, to Amnesty International, to the American Muslim council, announced their request Monday for information about the detainees at a Washington news conference.

Kate Martin is with a group called the Center for National Security Studies, a watchdog group that monitors civil liberties and national security issues. She and others are seeking information about those detained, through a federal law known as the Freedom of Information Act. "While certain aspects of the FBI investigation into the terrorist attacks do need to be secret," she said, "we do not live in a country where the government can keep secret who they arrest, where they are being held, the charges against them or their lawyers. The secret detention of more than 900 people over the past few weeks is frighteningly close to the practice of disappearing people in Latin America."

Ms. Martin says her group and others made a similar request to the Justice Department and the Federal Bureau of Investigation several days ago, but have not had a response.

Hundreds of non-citizens have been arrested or detained in the wake of the September 11 attacks on New York and Washington. But some investigators say only a handful of those now being held are suspected of having any involvement in or knowledge of the attacks. Justice Department officials say many of those detained are being held for immigration violations.

A new anti-terrorism bill signed into law last week by President Bush expands the authority of law enforcement officials to detain non-citizens seen as a threat to national security.

Attorney General John Ashcroft says the administration is determined to closely track non-citizens who violate immigration laws. "Let the terrorists among us be warned," he said. "If you overstay your visas, even by one day, we will arrest you. If you violate a local law, we will hope that you will, and work to make sure that you are put in jail and kept in custody as long as possible. We will use every available statute. We will seek every prosecutorial advantage. We will use all our weapons under the law and under the Constitution to protect life and enhance security for America."

Under the new anti-terrorism law, the attorney general has seven days to decide either to charge a detainee, initiate deportation proceedings or release the individual. However, Attorney General Ashcroft can order someone held indefinitely, if he certifies that person as a suspected terrorist.