site.btaUPDATED Venezuelan President Nicolas Maduro, Opposition Rival Edmundo Gonzalez Each Claim Victory in Presidential Election

Venezuelan President Nicolas Maduro and his opposition rival Edmundo Gonzalez were each claiming victory in a presidential election on Monday morning, after a vote marked by accusations of underhand tactics and isolated incidents of violence, Reuters reported.

Maduro has won a third term with 51% of the vote, the country's electoral authority said just after midnight on Monday, despite multiple exit polls which pointed to an opposition win.

The authority said opposition candidate Edmundo Gonzalez won 44% of the vote, though the opposition had earlier said it had "reasons to celebrate" and asked supporters to continue monitoring vote counts.

U.S. Secretary of State Antony Blinken expressed the United States' "serious concerns that the result announced does not reflect the will or the votes of the Venezuelan people," calling on the electoral authorities to publish a detailed tabulation of votes.

A poll from Edison Research, known for its polling of U.S. elections, had predicted in an exit poll that Gonzalez would win 65% of the vote, while Maduro would win 31%, Reuters said. Local firm Meganalisis predicted a 65% vote for Gonzalez and just under 14% for Maduro.

About 80% of ballot boxes have been counted, said national electoral council (CNE) president Elvis Amoroso in a televised statement, adding results had been delayed because of an "aggression" against the electoral data transmission system. The CNE has asked the attorney general to investigate the "terrorist actions" Amoroso said, adding participation was 59%. The CNE is meant to be an independent body, but the opposition alleges its acts as an arm of the government, Reuters said.