Ousted Madagascan leader Marc Ravalomanana arrived in Zimbabwe on Saturday ahead of a two-day summit set to launch a free customs union for Africa's main trading bloc.
Heads of state from the 19-member Common Market for Eastern and Southern Africa (COMESA) are set to approve the free customs union on Sunday after trade ministers agreed on a common external tariff deal.
Ravalomanana said he was invited by Africa's main trade bloc and the Zimbabwean government and that Madagascar needed support and help from the trade bloc, following his ouster in March.
"It was a coup. I'm sure COMESA will make a commitment so that I get my country back," he told reporters at Victoria Falls airport. "People of Madagascar are suffering. The illegal government is bad and the situation is deteriorating every day. We have to follow rules of democracy."
Ravalomanana this week dismissed a four-year jail term to which he was sentenced in absentia over his purchase of a $60m presidential jet.
On Sunday, Zimbabwean President Robert Mugabe will take over the COMESA chairmanship from outgoing chairman Kenyan President Mwai Kibaki.
Under the customs union deal, the 19 countries will impose the same tariffs on goods from outside the region. Raw materials and capital goods will travel across borders without tariffs, while intermediate products will be taxed at 10 percent and finished goods at 25 percent.