WASHINGTON, July 20 (Xinhuanet) -- Samuel Berger, former president Bill Clinton's national security adviser, is the focus of a criminal investigation that whether he improperly removed notes and classified documents from the National Archives during preparations for hearings before the Sept. 11 commission, media reports said Tuesday.

    Berger said he inadvertently took some documents from the archives but was not trying to withhold information from the commission, and his lawyers said he was cooperating with authorities, a USA Today report said.

    Three government officials who have been briefed on the investigation said Berger had removed handwritten notes and classified documents from a private room at the National Archives where he was preparing for his March 24 testimony.

    The Federal Bureau of Investigation (FBI) has conducted searches of Berger's home and office, but some of the documents hereviewed are still missing, the officials were quoted as saying.

    Some of the documents involved the Clinton administration's handling of intelligence surrounding terrorist plots to disrupt millennium celebrations in 1999 and identification of America's vulnerabilities at airports and seaports.

    "I deeply regret the sloppiness involved but had no intention of withholding documents from the Commission and, to the contrary,to my knowledge every document requested by the Commission from the Clinton Administration was produced," Berger said in a statement Monday night.

    The government officials said the investigation was set in motion by National Archives employees who reportedly witnessed Berger's actions in the room.

    A report in The Washington Post said the inspector general of the Archives began an investigation last October and turned it over to the FBI in January. FBI agents searched Berger's office and home safe, and the probe is continuing, Berger's attorney Lanny Breuer said.

    Berger spent three days at the Archives last summer and fall examining documents to provide the Clinton administration's responses to inquiries from the Sept. 11 commission, and later in October, the Archives notified Berger that documents were missing,the Post report said.

    The revelation about Berger, first reported by the Associated Press, comes days before the Sept. 11 commission releases its final report, which has become a political issue as both parties try to use its presumed findings to their advantage.

    Berger served as Clinton's national security adviser from 1997-2001 and has been advising Democratic presidential candidate John Kerry. Enditem