WASHINGTON — A divided Obama administration privacy panel has recommended ending the bulk collection of U.S. phone records, saying the controversial program amounts to an unlawful invasion of privacy that has not made Americans any safer.

The report by the independent five-member Privacy and Civil Liberties Oversight Board amounts to the sharpest official criticism yet of the National Security Agency program that collects and stores nearly every American phone record for querying in terrorism investigations.

“We have not identified a single instance involving a threat to the United States in which the telephone records program made a concrete difference in the outcome of a counterterrorism investigation,” the report said. “Moreover, we are aware of no instance in which the program directly contributed to the discovery of a previously unknown terrorist plot or the disruption of a terrorist attack.”

The report also said the program stretches to the breaking point the statutory language that the administration and a secret intelligence court have used to justify it.

“The unique characteristics of national security investigations do not warrant interpreting ‘relevance’ expansively enough to support the NSA’s program,” the report says, challenging the legal justification that every U.S. phone record is “relevant” to a terrorism investigation, the legal requirement for data collection under Section 215 of the Patriot Act.

It’s unclear, though, how much the report will influence firmly entrenched factions in the congressional debate over the fate of the program revealed last year by Edward Snowden. The three panelists who fully endorsed the report included a civil liberties activist, a former trade official in the Clinton administration and a retired judge appointed by President Jimmy Carter. The two other board members who dissented from key conclusions were Justice Department officials in the George W. Bush administration.

President Obama said last week he would begin asking a judge to approve each query of the database, and he also proposed moving the records into private hands.