Newly released files say a British newspaper received an anonymous call about "big news" in the United States minutes before the assassination of President John F. Kennedy.

A batch of 2,800 declassified documents includes a memo to the director of the FBI, dated November 26, 1963, about a call received by the Cambridge News on November 22.

It says the caller said that "the Cambridge News reporter should call the American Embassy in London for some big news, and then hung up."

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The memo says Britain's MI5 intelligence service calculated that the call came 25 minutes before Kennedy was shot in Dallas.

Anna Savva, a current Cambridge News reporter, says the paper has no record of who took the call. She said Friday that learning of the call was "completely jaw-dropping."

The newly released files are also shedding new light on shooter Lee Harvey Oswald and FBI Director J. Edgar Hoover's efforts to quell conspiracy theories about the fatal shooting of the nation's 35th president.

In the chaotic aftermath of the assassination, followed two days later by the murder of Oswald while in police custody, Hoover vented his frustration in a formerly secret report found in the files. It opened: "There is nothing further on the Oswald case except that he is dead."

But, reflecting on Oswald less than an hour after he died, Hoover already sensed theories would form about a conspiracy broader than the lone assassin.

"The thing I am concerned about, and so is (deputy attorney general) Mr. Katzenbach, is having something issued so we can convince the public that Oswald is the real assassin," he said.