WASHINGTON (AP) _ Fired scientist Wen Ho Lee was indicted today for removing nuclear secrets from a secured computer at the Los Alamos weapons lab where he worked, government officials said.

FBI agents immediately arrested Lee at his home outside of Los Alamos, N.M., and he was being taken to Albuquerque for an initial appearance later today before a federal magistrate, said FBI Special Agent Doug Beldon.

The indictment, which was expected to be unsealed later in the day, was issued by a federal grand jury in Albuquerque at the request of U.S. Attorney John Kelly. Justice Department officials declined comment.

While the government is prosecuting Lee for security violations, authorities have been unable to prove that Lee gave specific secrets to any country, including China, officials said.

The grand jury has been hearing evidence for months concerning alleged security violations by Lee at the Los Alamos lab where he had worked for nearly 20 years before being fired last March.

Kelly refused to comment on the case.

But officials familiar with the prosecutor's plans said the government planned to charge Lee with downloading secrets of American nuclear weapons and tests from a secured computer at the lab.

The government would further allege the scientist stored the secret data on computer tapes and removed them from the lab, the officials said.

Lee, a Taiwan-born computer scientist who worked on top-secret nuclear weapons programs, has been the center of a controversy involving alleged theft of nuclear secrets by China dating back to the 1980s. He has been the prime target of an FBI investigation involving alleged theft of nuclear secrets by China since 1996.

The Justice Department, which wrestled for months over whether to seek an indictment, was unable to develop evidence that Lee ever deliberately provided secrets to China, according to the sources.

The decision to prosecute Lee was made by Attorney General Janet Reno earlier in the week after a Saturday White House meeting of top administration officials including Energy Secretary Bill Richardson, FBI Director Louis Freeh, CIA director George Tenet and Samuel Berger, the president's national security adviser.

Richardson, who ordered Lee fired last March for security violations and has argued for criminal prosecution, said he would have no problem in declassifying certain nuclear weapons secrets needed in a trial once a decision was made to prosecute.

Mark Holscher, Lee's attorney, did not return telephone calls to his office in Los Angeles today.

Lee was fired for failing to safeguard classified material and not informing Energy Department officials about details of several trips to China.

At the time, Lee had been the target of a three-year FBI investigation concerning the alleged theft of secrets by China in the 1980s of details about the W-88 miniaturized nuclear warhead used on Trident submarines. Prosecutors, however, have never been able to clearly link Lee to the loss of the W-88 warhead secrets.

It was not until after he was fired that authorities discovered that Lee, around 1994, had improperly transferred thousands of computer codes _ the ``legacy codes'' that provide a history of nuclear weapons development _ from Los Alamos' highly secured computer system to his less-secure personal office computer.

Lee, who has rarely spoken publicly in the last nine months, acknowledged the computer file transfers, but maintained that he had put the codes into his office computer as a backup to safeguard against a computer crash. Los Alamos officials have scoffed at the explanation.

More recently, according to the government officials, it was determined that Lee also copied some of the computer codes onto tapes and taken them from the lab. Investigators have been unable to account for the movement of the computer tapes, according to the sources.

While the government's case focuses on the transfer of the legacy code files, no evidence appears to have surfaced to link Lee with the loss of the W-88 warhead material in the mid-1980s _ the case that put the spotlight on Lee at the outset.

In fact, the FBI's investigation into the W-88 warhead loss _ and even how extensive of a loss might, in fact, have occurred _ has been a subject of growing controversy in recent months.

Last summer a Senate report and then a report by the president's Foreign Intelligence Advisory Board criticized the FBI and Justice Department for focusing too narrowly on Los Alamos and on Lee in the investigation. These groups said the information about the warhead could have come from many other places.

In September, Reno ordered the investigation into the W-88 matter to broaden its focus to other labs, Energy Department sites and defense contractors.