Colombians are voting on Sunday in an election that is being billed as a test for the country's former leftist rebel fighters who gave up their arms last year and became a political party.

The Revolutionary Armed Forces of Colombia (FARC) disbanded after the 2016 landmark peace agreement, converting to a political party with the same initials.

Sunday's congressional poll is the first to see the former rebels participate in elections after a conflict that lasted more than 50 years and resulted in the death of more than 220,000.

The polls opened at 8am local time (13:00 GMT) and will close at 4pm (21:00 GMT).

The FARC are guaranteed 10 seats in Congress under the terms of the peace deal.

The party's campaign has been overshadowed by alleged attacks that at one point led to the suspension of the FARC campaign, as well as its presidential candidate withdrawing over health and safety concerns.

'Vicious cycle'

Among the major issues that are on voters' minds is corruption.

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Ariel Avila, Peace and Reconciliation Foundation, said that his organisation found that "there are more than 80 candidates for the Senate and the House of Representatives that have links with criminal organisation or are involved in corruption scandals ... or whose children or wives are currently jailed."

He said that all of these candidates have a good chance of winning.

"Many politicians enter these corruption circles to finance their campaigns," Avila told Al Jazeera.

"They buy out local community leaders and pay around 18 dollars per vote," he added.

"The culprits, in the end, are the citizens. They vote for the same corrupt parties, and then they complain about corruption. It's a vicious cycle."

Nearly 36 million Colombians are registered to vote in Sunday's election.