In caustic comments on internal FBI memos, bureau director J. Edgar Hoover referred to prominent columnist Jack Anderson with undisguised contempt, calling him "a jackal" as agents combed his articles for errors and hints about possible sources.

"This fellow Anderson and his ilk have minds that are lower than the regurgitated filth of vultures," Hoover typed on a memo dated April 30, 1951. It is one of hundreds from FBI files on Anderson.

Anderson was a Hoover critic. He once wrote that the aging director, running the bureau well into his 80s, should have resigned a decade before. Other journalists suggested the same, but Anderson delivered that and a long career's worth of critical assessments of the bureau in a blunt style that enraged FBI officials.

Documents turned over to The Associated Press under the Freedom of Information Act almost three years after Anderson's death include copies of his columns with critical notes in the margins, summaries of his movements while under surveillance, and FBI memos detailing efforts to find his sources who leaked information from deep inside government agencies.

The leaks fueled Anderson's Pulitzer Prize-winning column, "Washington Merry-Go-Round," and helped him produce stories on scandals including Watergate and the arms-for-hostages deal known as Iran-Contra.

Anderson's muckraking style, honed under the column's founder Drew Pearson, earned him a spot on President Nixon's enemies list, inspired Republican operatives to plot his murder and caused heartburn in Hoover's office at the FBI.

In one February 1971 memo, an unnamed agent went on for six pages, summarizing a radio interview in which the columnist "discussed the daily habits of the director and associate director ... including their means of transportation to FBI headquarters in the morning, the place where they take lunch and dinner."

The report said Anderson "concluded the interview by stating that the director should have retired 10 years ago and would better serve his country as an elder statesman who could offer advice to his successor."

FBI officials claimed incessantly over the years in internal FBI documents that the columnist got his facts wrong. "This is the greatest conglomeration of vicious lies that this jackal has ever put forth," Hoover scribbled next to a copy of one Anderson column.

The column said that Hoover had collected more than a quarter of a million dollars in royalties from three books researched and ghostwritten for him by FBI agents on government time.

Hoover, in another instance, used the same characterization when he tried to clear the air with House Speaker Carl Albert.

When Anderson reported that the FBI was keeping tabs on Albert's private life, Hoover wrote the speaker, "Characteristic of this jackal, none of the statements made about you and the FBI in this column has a scintilla of foundation."

When Anderson wrote that the U.S. crime conviction rate had slipped, Hoover's agents were on top of it. Hoover wrote top Nixon White House adviser John Ehrlichman to correct "the false impression" left by the columnist.

"There has been an increase in the number of persons convicted in certain major categories investigated," Hoover wrote Ehrlichman.

But Anderson was sympathetic to at least some of Hoover's campaigns, including his pursuit of Communists, the documents show.

In a Jan. 15, 1967, appearance on the "Long John Nebel" radio show, Anderson described himself as a liberal but urged so-called right-wingers to let Hoover and the FBI investigate handle investigations of suspected communists.

"I think he's been pretty careful about not violating civil rights," Anderson said of Hoover. "I have no quarrel with his investigation of communists. I would urge the extremists of the nation to let him continue to do it and not to interfere with him _ not to try to do it themselves."

Among the readers of Anderson's columns were Hoover defenders or administration loyalists who let the journalist know exactly how they felt in language even more candid than Anderson would have used in his columns. Copies were obtained and filed away by the bureau.

A profanity-laced letter from a reader to Anderson in 1971 says that "your rhetoric regarding the Honorable Richard Nixon" proves that the columnist was doing "everything in your power ... to tear this country apart."

"I demand, by copy of this letter to J. Edgar Hoover ... that you be put out of print," the letter concluded.

After Hoover's death, Anderson drew critical comments from readers. Continued...