The Organization of American States recommended on Sunday that Bolivia hold a new election after it identified "serious" irregularities in the voting system in a report that called into question the victory of President Evo Morales.
The preliminary OAS report, following an audit of the Oct. 20 vote, said that the international body could not verify the result after it found "clear manipulations".
"The manipulations to the computer system are of such magnitude that they must be deeply investigated by the Bolivian State to get to the bottom of and assign responsibility in this serious case," the report said.
The OAS said was not statistically likely that Morales had secured the 10 percentage point margin of victory needed to win outright and recommended Bolivia use new electoral authorities for any new vote.
Morales was declared the winner of the October election with a lead of just over 10 points over his rival Carlos Mesa, giving him an outright win. But there have been widespread protests since against the result after a near 24-hour halt in the count.
Morales, who came to power in 2006 as Bolivia’s first indigenous leader, has defended his election win and has said he would adhere to the findings of the OAS audit. He was expected to give a press conference on Sunday morning.