WASHINGTON (AP) - The U.S. government is slowly losing its ability to investigate a nuclear blast and quickly determine who was responsible and whether more bombs are out there, experts said in a report released Thursday.

While the nation has a vast web of nuclear labs, equipment and experienced personnel, those resources are focused more on managing the weapons stockpile and less on how to analyze the aftermath of a bombing, according to the report by the National Research Council.

"Although U.S. nuclear forensics capabilities are substantial and can be improved, right now they are fragile, under resourced, and, in some respects, deteriorating," said the council, an arm of the National Academy of Sciences. "Without strong leadership, careful planning and additional resources, these capabilities will decline."

In order to maintain and improve its ability to answer questions that would follow a nuclear blast, authorities must begin to pour more personnel and resources into the forensics program, the report said.

The study found that several of the nation's forensic facilities are old and outdated and were not built to meet current safety standards.

Nuclear forensics is a more narrow and specialized version of what television viewers see in popular crime shows, where analysts pour over murder scenes and bodies to try to solve the case. In a nuclear incident, experts would study any seized nuclear materials or devices, the radioactive debris from a blast and any detonation signals.

Scraps of information on who made the bomb, how, when and where they made it, and the technical details of its construction all provide critical insight into preventing or mitigating any future disaster.

The report released Thursday was an abbreviated version of a classified study finished in January. Since the beginning of the year, the report said, there has been some progress, including an increase in funding for nuclear forensics.

But it also found that there has been a decline in funding and skilled workers, and a need for better organization and high-tech equipment. The study recommended that the U.S. conduct more realistic exercises and devise better lab techniques and diagnostic equipment and a more complete database of nuclear materials, facilities and devices.

The National Academy of Sciences is an independent organization chartered by Congress to advise the government on scientific matters.

Online: Nuclear Forensics: A Capability at Risk: nap.edu/catalog/12966.html