An independent international audit of Bolivia’s disputed election concluded that former President Evo Morales’s officials resorted to lies, manipulation and forgery to ensure his victory.

Bolivia’s general elections on Oct. 20 were marred by “a series of malicious operations aimed at altering the will expressed at the polls,” auditors from the Organization of American States said in a 100-page final report released Thursday. Deliberate wrongdoing by election officials, combined with a series of errors and irregularities in the vote count, made it impossible to validate the results, the auditors added.

The election’s initial official results handed Mr. Morales, Bolivia’s first Indigenous president, an unprecedented fourth term in office, defying the constitutional term limits he himself had set. An unexplained delay in the vote count, however, triggered a wave of protests across Bolivia’s major cities, which eventually forced Mr. Morales to resign and flee into exile in Mexico .

Mr. Morales himself agreed to the international report. His government called on the O.A.S. to conduct a “binding” audit of the vote in an attempt to quell the unrest triggered by his victory.