On Tuesday, Choi briefed an extraordinary summit in the Nigerian capital Abuja of the Economic Community of West African States (ECOWAS) on the elections, which were a key step in efforts to reunite a country split in two by civil war in 2002.

The ECOWAS summit endorsed Choi's certification of Ouattara as president-elect, called on Gbagbo to "yield power without delay" in the best interests of his country, and hailed the UN's "key role" in the conduct of the elections under democratically acceptable conditions.

UN Secretary-General Ban Ki-moon, who repeatedly voiced his concerns over the current political standoff in Cote d'Ivoire, joined the world powers in recognizing Ouattara as the new president of the West African country after the runoff presidential election last Sunday, but Gbagbo refused to step down.

The vote was a major step in the efforts to reunite the world's largest cocoa exporter after it was split by civil war in 2002 into a government-controlled south and a rebel-held north.

Cote d'Ivoire's presidential elections have been delayed since 2005 due to tension between the rebel-held north and the south.

However, it has generated a new crisis after the Constitutional Council threw out the Independent Electoral Commission (IEC) proclamation of Ouattara as the victor, citing irregularities in his northern base, and awarded the victory to Gbagbo.

On Wednesday, Choi publicly rebutted Gbagbo's claims of irregularities point by point, noting that even if contested tally sheets were thrown out, it was still clear that Ouattara had won.

The complaints, used by the Constitutional Council, were based on two arguments: that the use of violence in nine departments in the north prevented people from voting, and that tally sheets there lacked the signature of the presidential camp's representatives.

On the first issue, Choi stressed that a voter turnout as high as 81 percent could not possibly mean that there was sufficient violence to prevent people from voting, while reports on violence collected by the UN mission in Cote d'Ivoire (UNOCI) shows that there were fewer violent acts in the north than in the west.

On the second issue, he said he reviewed all tally sheets in the concerned departments and eliminated all those which lacked the signature of Gbagbo's representatives.

"The upshot was that, even such an exercise did not alter in any significant way the outcome of the second round," he added. "On this basis, I remain absolutely certain that I have found the truth concerning the will of the Ivorian people as expressed on Nov. 28."

Choi said he used three methods "to arrive at the absolute conviction regarding the winner" -- First he deployed 721 UNOCI members throughout the country to find voting trends as early as possible; Secondly, he collected results from the 19 regional local electoral commissions, and these further confirmed the trends that it was almost certain who had won and who had lost.

Finally, UNOCI examined all 20,000 tally sheets to see if there was a trace of fraud or manipulation, especially if they had been signed. A certain number had to be discarded but these were not concentrated in some particular regions but were spread randomly.

UNOCI, with a current strength of over 9,000 uniformed personnel, has been supporting reunification efforts, of which November's vote, and the first round held in October following five years of delays, was a principal step.