In a speech read on his behalf by his special aide, Joyce Mogtari Bawa, at the National Cadres Conference in Koforidua, the former president said “cronyism and nepotism have become government policy."
“This conference is being held at a time were many acts of corruption being complained about have been largely cleared and mostly go uninvestigated," he said.
"Unfortunately, society has remained silent. There is very little being said about all of these ills that we are currently grappling with.”
Mr Mahama is leading the National Democratic Congress into the 2020 election.
He lost the 2016 polls by over one million votes to then candidate Akufo-Addo, becoming the first president in Ghana to lose a re-election bid.