The FBI on Tuesday unexpectedly posted old case files of its investigation into the Clinton Foundation from 2001 — leading an already furious Clinton campaign to question the agency’s “odd” timing.

“Absent a FOIA litigation deadline, this is odd,” tweeted Clinton spokesman Brian Fallon. “Will FBI be posting docs on Trump’s housing discrimination in ’70s?”

FOIA refers to the Freedom of Information Act.

The FBI did not immediately offer an explanation.

Most of the 129 pages released Tuesday focused on the FBI’s criminal probe into Bill Clinton’s controversial 2001 pardon of financier Marc Rich on his final day as president.

The FBI closed the case without ever filing charges.

The newly released documents included interview notes, case updates, subpoena records and grand-jury scheduling.

All were heavily redacted, but there were enough snippets to demonstrate that the FBI had undertaken a sweeping investigation into charges that the pardon was a payoff.

It was widely reported at the time that Manhattan US Attorney Mary Jo White launched a grand-jury investigation into whether Rich’s songwriter ex-wife, Denise, got the pardon by making donations to Democratic Party accounts and the Clinton Foundation.

“New York is conducting a sensitive investigation concerning possible corruption surrounding the pardons granted by former US President WILLIAM CLINTON,” said one case update on March 29, 2001.

The investigation was homing in on a dinner in January 2001 at an identified restaurant where the pardon may have been hatched.

“It appears that required pardon standards and procedures were not followed,” said a Feb. 15, 2001, FBI memo from its New York Criminal Division “White Collar Branch,” noting that then-Deputy Attorney General Eric Holder was the “only person” at the Justice Department notified of the pardon.

Hillary Clinton’s aides have been questioning why FBI Director James Comey dropped a bombshell on the presidential race last week by announcing the agency had found new Clinton e-mails on a laptop shared by aide Huma Abedin and Anthony Weiner, her estranged husband.

The FBI said it was required by FOIA to release the documents.

“The FBI’s Records Management Division receives thousands of FOIA requests annually which are processed on a first in, first out (FIFO) basis,” they said. “By law, FOIA materials that have been requested three or more times are posted electronically to the FBI’s public reading room shortly after they are processed.”