The FBI admitted last week it misused its powers through national security letters in 2004 to access the cell phone records of New York Times reporters Ray Bonner and Jane Perlezy, as well as Washington Post staff writer Ellen Nakashima and researcher Natasha Tampubolon, who were in Indonesia working on a story about Islamic terrorism.

But the apology didn't contain an explanation as to why the FBI felt it necessary to comb reporters' telephone records, says Reporters Without Borders, an international group with offices in Washington.

"We urge (the FBI) to be transparent about the reasons to obtain the records with such urgency and secrecy," the press freedom organization said in a statement. "We urged the bureau to refrain from using similar procedures in the future. Improper monitoring of reporters is harmful to a free press and undermines the free flow of information."

FBI Inspector General Glenn Fine said he made the discovery while reviewing alleged misuse of national security letters to demand personal records.