UN chief Ban Ki-moon on Friday called once again on Ivory Coast strongman Laurent Gbagbo to step down and respect the "genuine will" of the west African country's people.

The United Nations has recognised Gbagbo's rival Alassane Ouattara as victor in Ivory Coast's November presidential election and has repeatedly urged Gbagbo to accept to defeat and leave office.

"I therefore urge again the Gbagbo camp to fully respect the will of the Ivorian people," Ban told journalists on the sidelines of the World Economic Forum in Davos.

Ban also said he was concerned that "some differences of opinion are now surfacing in the African Union", a body which had previously been all but united in its support for Ouattara's victory.

UN observers say at least 271 people have been killed in the Ivory Coast since the disputed election result, which saw both Gbagbo and Ouattara declare themselves president and led to an armed stand-off.