Roman Catholic Archbishop of Bulawayo Pius Ncube says the political and economic situation in Zimbabwe has reached "life-threatening proportions".
He accused President Robert Mugabe's government of not taking responsibility for the deepening crisis.
He says there is almost no fuel in the country, and every day, people are reduced to hunting for a loaf of bread.
The archbishop said it had reached a point where regional political intervention was now needed.
Talks between Zimbabwe's ruling party and the opposition resumed in South Africa this week, with President Thabo Mbeki responsible for mediating.
But Archbishop Ncube said he doubted that President Mugabe would step down as Zimbabwe's leader, in return for an amnesty deal.
"Mugabe is a man who is a megalomaniac. He loves power, he lives for power. Even his own party are pleading with him - 'Please stand down, you've done enough good'.
"According to Zanu-PF he's done a lot of good, according to me, he's done a lot of evil."
Archbishop Ncube was speaking in Johannesburg as the Solidarity Peace Trust, a church-based non-governmental organisation, launched a new report on the crisis in Zimbabwe.
In its report, the Solidarity Peace Trust, says there has been increasing state repression against dissenting voices since March when many members of the opposition were arrested and beaten.
It also says the governing party in Zimbabwe, Zanu-PF, has lost much of its political legitimacy.
Mr Mugabe blames the worsening economic crisis on a Western plot to remove him from power.