By Edward McAllister
OUAGADOUGOU (Reuters) - Burkina Faso opposition candidate Zephirin Diabre said President Roch Kabore is orchestrating a "massive fraud" to secure re-election in Sunday's presidential vote, and that he will not accept results marred by irregularities.
Diabre, a 61-year-old former finance minister, is one of the main challengers in a field of 12 who are seeking to unseat Kabore in Burkina Faso's second democratic elections since a 2014 revolution.
Diabre told a news conference on Saturday that ruling party agents are paying women in markets to hand over voting cards so that someone else can vote for them. He waved aloft a video on his mobile phone purportedly showing this occurring, but did not provide further evidence of wrongdoing.
Diabre said his party will file a complaint with the state prosecutor and asked the electoral commission to end the practice.
"The massive nature of the phenomenon may undermine the serenity and integrity of the results of the November 22 elections," Diabre said.
The president of Kabore's MPP party, Simon Compaore called the allegations "false".
Electoral commission representatives did not immediately respond to requests for comment.
The head of a mission by the Economic Community of West African States (ECOWAS), which arrived to meet opposition members as Diabre's conference was ending, said that he had seen no evidence of fraud.
"We have been blessed to witness a very calm and gentlemanly campaign. We have no worries of fraud," the former prime minister of Guinea, Kabine Komara, told Reuters.
Analysts expect a tight race between Kabore, Diabre and another candidate, Eddie Komboigo, with the possiblity of a second round election if no candidate wins more than 50% of the vote on Sunday.
At least 400,000 people, or nearly 7% of the Burkina Faso electorate, will not be able to vote due to an Islamist insurgency linked to al Qaeda and the Islamic State that has forced a million people to flee.
By order of the electoral commission, polling stations will not open in hundreds of villages hard-hit by attacks in the north and east.
(Additional reporting by Thiam Ndiaga; Writing by Bate Felix; Editing by Frances Kerry)