FBI agents seeking a warrant for their investigation of espionage suspect Wen Ho Lee were sent back for additional evidence three times by Justice Department attorneys but "never came close" to meeting legal standards for a search or a wiretap, department officials said yesterday.

The evidence against Lee and his activities at the Los Alamos National Laboratory was so scant, one high-ranking department official added, that no one who reviewed the case thought a warrant or wiretap could be justified. "Everybody thinks it was either a `no,' or a `no way,' " the official said.

Attorney General Janet Reno said Thursday that she fully supported the decision of career attorneys in the department's Office of Intelligence Policy Review not to seek a warrant or wiretap against Lee because investigators could not establish probable cause that he was engaged in illegal acts. The department's refusal to ask the secret Foreign Intelligence Surveillance Court to authorize a search or a wiretap has triggered a barrage of intense criticism on Capitol Hill, with leading Senate Republicans and at least one Democratic senator calling on Reno to resign.

Sen. Richard C. Shelby (R-Ala.) has called Reno's handling of the case "indefensible" and said evidence of Chinese espionage at the nation's nuclear weapons laboratories -- highlighted this week in the findings of a House select committee -- should have prompted the Justice Department to seek a wiretap and a search warrant. Shelby, chairman of the Select Committee on Intelligence, and other leading Republicans have charged for months that the administration dragged its feet in reacting to allegations of Chinese espionage at the weapons labs in order to protect its policy of engaging the Chinese.

The GOP's sustained attack, joined in recent weeks by some Democrats, came to focus in part on why the Justice Department in 1997 refused to even apply for a warrant to search Lee's office after it was disclosed last month that Lee had transferred highly sensitive nuclear weapons computer programs from Los Alamos's classified computer network to his vulnerable desktop computer.

In their attacks, the GOP critics have pointed out that the department has requested wiretaps or search warrants from the Foreign Intelligence Surveillance Court 3,657 times over the past five years and been turned down only once. Given that success rate, the critics contend, Reno should have at least asked the court for a search warrant.

But department officials said that the attorney general is required by law to determine probable cause before asking the court for a warrant or a wiretap and cannot simply pass the decision along for a judge to make. The officials also said that Shelby and other critics fail to understand that virtually all of the 3,656 wiretaps or search warrants approved under the Foreign Intelligence Surveillance Act (FISA) were obtained against foreign intelligence targets, meaning far less evidence was required.

To obtain a FISA wiretap or search warrant against a foreign operative, they said, FBI counterintelligence agents only have to show that an individual is engaged in clandestine intelligence gathering on behalf of a foreign power. But the standard is much higher for American citizens. To obtain a FISA warrant or wiretap against Lee, the officials said, FBI agents needed to show probable cause to believe that Lee not only was engaged in clandestine intelligence gathering on behalf of China but also was "knowingly" violating federal law.

Lee has denied ever passing classified information to the Chinese.

Lee was targeted as a potential suspect by Energy Department intelligence officials in 1996 after the CIA obtained a document from a Chinese agent that contained dimensions of the W-88 warhead, which was designed at Los Alamos. The CIA later determined that the document was a plant by Chinese intelligence, the select committee revealed this week.

While the document made no reference to either Lee or Los Alamos, it was dated 1988, the same year Lee traveled to Beijing and delivered an authorized scientific paper at a conference.

In trying to obtain a FISA warrant against Lee in 1997, FBI agents and Energy Department intelligence officials theorized that there may have been some connection between Lee's trip and the design information contained in the 1988 document. But Justice Department attorneys believed there was no evidentiary value in that coincidence.

The FBI agents and DOE intelligence officials also cited a call that Lee had placed in 1982 to a Lawrence Livermore National Laboratory scientist, also Taiwan born, who was then under investigation for espionage. But the call, which was intercepted by the FBI, turned out to have been innocent in nature and had no value in establishing Lee's involvement in espionage on behalf of China, according to one administration official.

CAPTION: Wen Ho Lee, the nuclear weapons lab scientist who was investigated by the FBI on suspicion of espionage for China, at his Los Alamos home last month.