Christopher Steele worked for the Department of Energy's National Nuclear Safety Administration (NNSA) and was in charge of ensuring the laboratory followed federal nuclear safety requirements. He was put on administrative leave without pay in November, said the Project on Government Oversight, which has made public charges about a number of problems at the lab.

A spokesman for NNSA confirmed that Steele was on administrative leave but said the move had nothing to do with the charges outlined by the watchdog group. Officials at the Los Alamos National Laboratory would not comment and Steele was not immediately available for comment.

"LANL was unhappy with him because he wasn't signing off fast enough on safety requirements," said Peter Stockton, a senior investigator with the group in Washington, D.C.

Steele charged in a memo in August 2001 the lab had conducted unauthorized and unsafe storage of nuclear waste, Stockton said.

"They believed he was a thorn in their side, and bang, he's gone," Stockton said.

Steele was investigating, among other things, the storage of radioactive waste - mostly clothing, tools and other contaminated items - that was being kept temporarily in a steel shed. The storage did not meet federal safety requirements, Stockton said.

The Energy Department fined the lab $220,000 in late December for a serious breach of safety.

Dennis Martinez, deputy director for Energy Department's NNSA office in New Mexico, said he could not release information relating to Steele's administrative leave, calling it "a personnel matter."

"There is absolutely no connection between Chris Steele's status today and the (nuclear safety violation)," Martinez said.

In a separate incident, two lab investigators were fired in November after issuing a report that charged the lab with extensive corruption and mismanagement.