The United States called Thursday on the Ivory Coast to use a "transparent and legal mechanism" for holding ousted strongman Laurent Gbagbo to account for alleged human rights abuses.

"We've said all along that Laurent Gbagbo and anyone who has been involved in possible human rights abuses should be held accountable for their actions," State Department spokesman Mark Toner told reporters.

"And so we would urge for a transparent and legal mechanism for that to take place," he said.

Alassane Ouattara, the internationally-recognized winner of November 28 elections, has vowed to prosecute Gbagbo, who officials said was moved on Wednesday from Abidjan to the north of the country where he is under UN guard.

"Now it's time for Ivorians to turn the page and to move forward under the leadership of President Ouattara," Toner said.

"We believe he has a good plan for the country, both to help it rejuvenate economically, but also to stabilize politically. And we urge all Ivorians to get behind him and to support him in his efforts," Toner said.

William Fitzgerald, a senior State Department official, told reporters meanwhile that Phillip Carter, the US ambassador in the Ivory Coast, has been pushing reform of the security sector, adding Ouattara did not yet control all the security forces who support him.

(AFP)