A former national security adviser to President Clinton, Samuel Berger, stashed highly classified documents under a trailer in downtown Washington in order to evade detection by National Archives personnel, a government report released yesterday said.

The report from the inspector-general for the National Archives, Paul Brachfeld, said Mr. Berger executed the cloak-and-dagger maneuver in October 2003 while taking a break from reviewing Clinton-era documents in connection with the work of the so-called September 11 commission.

“Mr. Berger exited the archive onto Pennsylvania Avenue,” the report says, recounting the story the former national security chief told investigators. “He did not want to run the risk of bringing the documents back in the building. … He headed toward a construction area on 9th Street. Mr. Berger looked up and down the street, up into the windows of the archives and the DOJ, and did not see anyone. He removed the documents from his pockets, folded the notes in a ‘V’ shape, and inserted the documents in the center. He walked inside the construction fence and slid the documents under a trailer.”

According to the report, Mr. Berger said he retrieved the documents after leaving the archives complex for the evening and took the papers to his office. It is not clear how long the documents were unattended at the construction site, but the report suggests it was a few hours, at most.

The former national security chief said he cut three documents up in his office and discarded them in the trash. Mr. Berger returned two other documents after archivists notified him that some records were missing, but his efforts to retrieve the others from the trash collector were unsuccessful.

Last year, Mr. Berger pleaded guilty to a misdemeanor charge of mishandling classified information. A magistrate, Deborah Robinson, sentenced the international business consultant to two years’ probation and ordered him to surrender his security clearance for three years. Prosecutors and defense lawyers had agreed on a fine of $10,000, but the magistrate boosted it to $50,000.

“Mr. Berger made mistakes in his efforts to prepare thoroughly for the 9-11 Commission. But he has taken full responsibility for his conduct, he long ago provided everything that government investigators needed, and he has fully paid his debt to society,” the former security chief’s attorney, Lanny Breuer, said in a written statement yesterday. “Like the court, the government, and the 9-11 commission, Mr. Berger considers this matter closed, and he is pleased to have moved on.”

Mr. Breuer did not address the trailer-related episode, but stressed that the Justice Department determined that no original information was lost as a result of Mr. Berger’s actions and that he did not intend to hide any of the records.

A leading authority on classification policy, Steven Aftergood of the Federation of American Scientists, said Mr. Berger’s behavior was reminiscent of a “dead drop,” when spies leave records in a park or under a mailbox to be retrieved by a handler.

“It seems deliberate and calculated,” Mr. Aftergood said. “It’s impossible to maintain the pretense that this was an act of absentmindedness.”

All five documents Mr. Berger removed were versions of an after-action report about the foiled “millennium plot” to bomb the Los Angeles International Airport and other sites. The internal review, by a top counterterrorism official, Richard Clarke, reportedly found that luck was the major factor in disrupting the plot and that more attacks were likely.

Mr. Berger has admitted placing classified documents and his notes, which were also presumed classified pending a review, into his suit pockets to carry them out of the archives. However, the inspector general’s report resurrects claims that Mr. Berger may have removed some papers by placing them in his socks.

An archives staffer reported that Mr. Berger took frequent bathroom breaks and was seen in a hallway “bent down, fiddling with something white, which could have been paper, around his ankle.”

Mr. Berger later told investigators that any fidgeting near his feet was due to difficulties he has keeping his footwear tidy. “He stated his shoes frequently come untied and his socks frequently fall down,” the report said.

A person close to Mr. Berger said yesterday that the so-called docs-in-the-socks incident never took place. “It simply didn’t happen. It was wrong. The Justice Department determined it was wrong,” the Berger ally, who asked not to be named, said.

The inspector general’s report, released under the Freedom of Information Act, was heavily redacted on national security and privacy grounds. The internal watchdog appears to have focused on whether archives personnel were too deferential to Mr. Berger by contacting him about the missing documents before notifying the FBI.

Names of archives employees were deleted from the report, as were those of any National Security Council staffers involved.

One employee “did not believe there was enough information to confront someone of Mr. Berger’s stature” and delayed acting as a result, the report said.

When the allegations about the missing document were leaked to the press in 2004, Mr. Berger resigned from a team advising the Democratic presidential nominee, Senator Kerry of Massachusetts.

At that time, Mr. Berger insisted that he accidentally removed and destroyed the records. When he pleaded guilty last year, the former national security chief admitted he acted intentionally.