Libyan leader Muammar Gaddafi has vowed to pursue his vision of a United States of Africa, in his inaugural address as the new chairman of the African Union.
Col Gaddafi was elected by the heads of state of the 53-member union behind closed doors at a summit in Ethiopia.
A BBC correspondent at the summit says Col Gaddafi was seen to be the obvious choice, but some delegates are uneasy about his nomination.
Col Gaddafi replaces the Tanzanian President, Jakaya Kikwete.
Wearing a golden brocade robe and cap, Col Gaddafi sat with the traditional African leaders who accompanied him at the front of the room, rather than in the seat for the Libyan delegate.
Col Gaddafi attended the summit with an entourage of seven local monarchs
"I shall continue to insist that our sovereign countries work to achieve the United States of Africa," he said in his inaugural speech.
But he admitted that African leaders were "not near to a settlement" on the issue.
He told fellow summit leaders that his unity project would be approved at the next meeting in July unless there was a majority against it, reports the BBC's Elizabeth Blunt from Addis Ababa.
The AU normally relies on consensus in reaching decisions, but Col Gaddafi introduced what he described as the Islamic concept that "silence is approval," she said.
Under this principle, at least two-thirds of AU leaders would have to actively oppose Col Gaddafi's proposals, rather than simply ignoring his ideas, she added.
But an expert on the African Union called the vision of the United States of Africa a "ludicrous fantasy on the part of [Col] Gaddafi."
Kathryn Sturman at the South African Institute of International Affairs said many African leaders would not be prepared to give up their national sovereignty to join the proposed single-state federation proposed by the Libyan leader.
Ms Sturman said the chair of the group does not have any singular decision-making power, and cannot push through any changes without the consensus of the other leaders.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.