La Paz, Oct 22 (AFP) The main opposition candidate in Bolivia's presidential election refused Monday to recognize results that seemed set to give victory to long-time incumbent Evo Morales, as election monitors voiced "deep concern".

Carlos Mesa, a former president who came a close second to Morales in Sunday's polls -- forcing a run-off according to preliminary results -- denounced revised results released by election authorities as a "fraud".

Election monitors from the Organization of American States earlier expressed "deep concern and surprise" at changes to the election count that showed Morales closing in on an outright victory in the first round.

"The OAS mission expresses its deep concern and surprise at the drastic and hard-to-explain change in the trend of the preliminary results revealed after the closing of the polls," it said in a statement.

Preliminary results released late Sunday showed neither Morales nor Mesa with a majority and "clearly indicated a second round," the OAS mission said. (AFP)

(This is an unedited and auto-generated story from Syndicated News feed, LatestLY Staff may not have modified or edited the content body)