In the capital Asuncion, several hundred followers of self-proclaimed “anti-system” candidate Payo Cubas had demonstrated Monday, clashing with police outside the electoral authority’s headquarters.

“There is no possibility of fraud,” electoral tribunal spokesman Carlos Ljubetic told reporters.

“The results of the election are the expression of the citizenry, whether we like it or not.”

Nearly 70 protesters were arrested overnight across the country for alleged disturbances to public order, according to police.

Several roadblocks were cleared by Tuesday morning.

Cubas had denounced alleged irregularities in Sunday’s poll, in which Pena won 42% of the vote, followed by center-left challenger Efrain Alegre with 27%.

Cubas garnered 22% of the vote, higher than expected. He has not filed any official complaint to back up his claims of a “monumental fraud.”

The tribunal also lodged a complaint against protesters “who tried to block trucks carrying ballot boxes,” Ljubetic added.

Pena on Tuesday called for calm and lambasted a “political sector that advocates anarchy, instability and the dismantling of institutions. It is part of a strategy to capitalise on the anger, the frustration, the lack of opportunity of many people.”