The African Union summit has opened in Accra, Ghana, focusing this year on the idea of a pan-African government.
The Accra summit is the AU's ninth in five years
Libya's Colonel Muammar Gaddafi is championing the idea, but many African leaders do not support his initiative.
Some leaders fear the issue will push the crises in Zimbabwe, Somalia and Darfur off the agenda.
Ghana's President John Kufuor said in his opening speech that the question of unifying Africa was not in doubt, but the key issue was how to attain it.
"I am confident that at the end of our deliberations, we should be able to arrive at a common understanding on the sort of continental government we want for ourselves, and a roadmap with timelines on its realisation," he said.
But some leaders believe that by putting so much energy into the unity debate, urgent issues are being neglected.
The Nobel Peace Prize winner, Desmond Tutu, has put his name to a petition calling for the presidents to focus their attention on the conflict in the Sudanese region of Darfur.
The petition says African heads of state have a decision to make - be weak and turn away while innocent people suffer, or be strong and take responsibility for protecting them.
Sudanese President Omar al-Bashir is missing the summit following the death of a close aide in a car crash,
His absence will not help change the minds of those who doubt all the African leaders are willing to work closely together, let alone form a united government, reports the BBC's Will Ross in Accra.
On the eve of the three-day summit, foreign ministers heard critical reports on the way the AU handles money.
A report by the international auditing firm Ernst and Young found that the African Union could not account for almost $3m it spent on a conference for African intellectuals.
Col Gaddafi hopes to get AU backing for his grand idea
The firm also said the AU could not verify how much it paid members of the Pan-African Parliament, an AU body.
Another report, by AU financial experts, showed that only seven of the 53 member states were up-to-date with their payments to the AU.
This summit is the ninth since the AU was created five years ago.
"For Africa, the matter is to be or not to be," President Gaddafi told students at the University of Ghana on Saturday.
"My vision is to wake up the African leaders to unify our continent," he said, describing himself as a "soldier for Africa".
The idea of a single pan-African government was first promoted by Kwame Nkrumah, who led Ghana to independence in 1957, and the Libyan leader has long been an enthusiastic proponent of the idea.