The conduct of elections in Nigeria this month has received generally positive reviews.

But results of the April 16 presidential poll published by the Independent National Electoral Commission (INEC) have been rejected by the leading opposition candidate, General Muhammadu Buhari, a former military dictator who came in second in the race.

One of his most prominent supporters, Nassir El-Rufai, and former government minister, says the announced results do not accurately reflect the votes that were cast. Speaking at the Atlantic Council in Washington, DC, on Tuesday, El-Rufai said there was extensive fraud during the vote-counting process. He said election rigging occurred when ballot boxes were moved from polling stations to collation centers.

"This is not something election observers see or understand," Rufai told AllAfrica.

"It will serve Nigeria well and help bring lasting peace to our country if these flaws are recognized instead of declaring the elections as near-perfect," he said. "Buhari has a huge following - many who see in him some hope for clean governance." Buhari received nearly 12 million votes, according to the official count, Rufai said. The "expectations and anger" of his supporters must be addressed.

Rufai presented a 10-page paper detailing these charges, which included a voting tally sheet. He said: "It shows how the votes are changed before transferring to a 'clean copy' that goes to the collation officers. It was seized from the official at the Wuse Police Station on the day of the presidential elections and was used in the computation of the legislative elections a week earlier."

The Nigerian 2011 Elections - An Opportunity Lost? (.PDF)