Heads of state are attending the African Union summit to discuss plans for a United States of Africa which does away with national borders.

The official agenda item is an idea first proposed four decades ago: "a united Africa". Although most African countries have accepted the idea of a borderless continent-wide entity, due to disputes on how to proceed, it remains no more than a slogan.

A 2006 African Union (AU) report advocates achieving a United States of Africa by 2015 with the AU transforming into a government.

Some heads of state such as Libya's Moammar Ghadafi are calling for an immediate formation of a new, pan-African government.

Alpha Oumar Konare, the departing chair of the African Union Commission, said that over the past five decades, numerous documents had been adopted calling for a pan-African body, but that individual states had failed to carry them out.

Unofficially the key discussion will be about the things pulling Africa apart, allegations of genocide in Sudan's Darfur region and the brutal crackdown in Zimbabwe.

Protests have been banned until the final day of the three-day summit on Tuesday, and 2,000 policemen have already fanned out across the Ghanaian capital.

Planned protests include one calling for an end to the violence in Darfur and a second by Zimbabwean activists decrying Zimbabwean President Robert Mugabe.

On the sidelines of the summit, South African President Thabo Mbeki is expected to present a report on the progress of his attempt to mediate a solution in Zimbabwe.

Earlier this year, Zimbabwe's top opposition leader was hospitalized after police violently broke up a meeting he was attending.