Presidents Uhuru Kenyatta is among leaders who will attend the swearing-in of Uganda's Yoweri Museveni on Thursday.
Uhuru will head to Uganda from Kigali, Rwanda, where he attended the .
Presidents John Magufulu (Tanzania) and Paul Kagame (Rwanda) are also expected to grace the occasion.
Museveni, 71, will be inaugurated in Kampala following his win in the February 18 general election,
rule.
He garnered 60.75 per cent of the votes while Opposition leader Kizza Besigye got 35 per cent.
Besigye said the vote was rigged but the electoral commission said the process was fair.
Besigye's party - Forum for Democratic Change -
swore him in as President on Wednesday but he was later arrested while addressing a crowd in the capital.
Patrick Onyango, a police spokesman, said a court order issued in April barred Besigye and the FDC from engaging in anti-government protests.
"Today Besigye went ahead and had a procession in downtown Kampala, by doing so he was disobeying lawful orders of the court," he said.
The police spokesman refused to comment on the FDC's mock ceremony.
Since election day, Besigye has been kept under virtual house arrest by police, putting spiked barriers near his home and vetting his visitors.
Watch:
Ingrid Turinawe, a senior FDC official, told Reuters of Besigye: "Whoever is swearing in tomorrow, or some other time we're not concerned ... we have a legitimate president."
Over the past days, squads of military and police personnel have been patrolling the capital Kampala on suspicion the opposition intends to hold protests and thwart Museveni's inauguration on Thursday.
Last week the government banned live media coverage of all opposition activities, citing the court order barring anti-government protests. Opposition supporters have vowed to defy that order.
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