The top U.N. envoy in Ivory Coast, Choi Young-jin, said Obasanjo was there to "discuss the post-electoral crisis" according to the AP.
The international community has said that Alassane Ouattara won the country's presidential election but the incumbent leader Laurent Gbagbo has refused for more than a month to concede defeat and cede power.
A delegation of presidents from three other West African countries visited Gbagbo twice in an effort to persuade him to hand over power. Gbagbo, though, has rebuffed the efforts and human rights groups accuse his security forces of abducting and killing political opponents.
The 15-nation regional bloc ECOWAS had threatened to use military force to oust Gbagbo, but support for such an operation is unclear. On Friday, the president of Ghana said his country is not able to send troops.
The former Nigerian president left office in 2007 after term limits kept him from running again. The handover to his successor was Nigeria's first civilian-to-civilian transfer since independence from Britain in 1960.
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