South African authorities are preventing ousted Madagascan leader Marc Ravalomanana from leaving the country, his lawyer said Wednesday, denouncing a ploy to bar him from returning home to run in upcoming polls.

Brian Currin said his client, who is being investigated by South African prosecutors over police killings in the unrest that led to his toppling in 2009, was asked on September 7 not to leave South Africa and stripped of his passport.

"This is a desperate, disingenuous and malicious attempt without any merit to stop Marc Ravalomanana returning to Madagascar to register as a contestant in forthcoming elections," Currin said.

"We are preparing papers to have the interdict set aside," the lawyer told AFP.

Ravalomanana has made several failed attempts to return to the Indian Ocean island which he fled following a coup led by current strongman Andry Rajoelina in March 2009.

The two rivals met twice in the Seychelles recently in a bid to iron out differences and agree on Ravalomanana's return, a key step in a plan brokered by the regional bloc SADC for a May 2013 presidential election.