Zimbabwean Roman Catholic Archbishop Pius Ncube says he accepts that his opposition to Zimbabwe's President Robert Mugabe may cost him his life.
Archbishop Ncube says Zimbabweans are desperate
"The church has a prophetic role to speak the truth when no-one else dares to," the Archbishop of Bulawayo told the UK's Daily Telegraph newspaper.
Meanwhile, a crackdown on aid groups suspected of opposing the president has begun, state media reports.
All non-governmental organisations must now reapply for their licences.
Last month, the UN said that 1.4m Zimbabweans would need food aid this year, as harvests were only due to meet one-third of the country's requirements.
Mr Mugabe blames the worsening economic crisis on a Western plot to remove him from power.
Archbishop called for mass street protests in March and said people must be prepared to stand in front of "blazing guns" to force Mr Mugabe from power.
Earlier this month, a two-day strike called by trade unions in protest about the worsening economic crisis was poorly observed.
Zimbabwe has the world's highest annual rate of inflation - 1,700% - and only one person in five is in full-time work.
"Mugabe is mad for power and he will cling to it even if it means destroying the economy and destroying Zimbabwe," Archbishop Ncube said.
As Zimbabwe marks 27 years of independence on Wednesday, the archbishop said many people are too depressed to go on living.
"Mugabe is an evil man, a bully and a murderer. I will not be bullied or bought by him.
"I accept that it may mean that I lose my life."
The BBC's Grant Ferrett says the archbishop's impatience for change and defiance is a legacy of the Gukurahundi massacres of the 1980s, when Mr Mugabe attempted to stamp out potential threats to his new government.
An estimated 20,000 people were killed in Zimbabwe's southern Matabeleland region, most of them civilians.
As a young priest, he witnessed the suffering and was desperate to speak out, but his church superiors stopped him.
Now that he is in charge, the archbishop is determined not to watch in silence again, our reporter says.
Information Minister Sikhanyiso Ndlovu ordered the NGO crackdown, saying some organisations were using relief activities as a cover for an opposition-led campaign to overthrow the government.
"Pro-opposition and Western organisations masquerading as relief agencies continue to mushroom," state radio quoted him as saying.
"The government has annulled the registration of all NGOs in order to screen out agents of imperialism from organisations working to uplift the wellbeing of the poor."
Last month, a prayer meeting in the capital, Harare, attended by opposition leaders and activists was broken up by police, leaving two people dead.
Scores of activists, including Movement for Democratic Change (MDC) leader Morgan Tsvangirai, were arrested and assaulted in police custody.
Archbishop Ncube also accused other African leaders of failing to exert pressure on Mr Mugabe to relinquish power.
Southern African leaders have appointed South Africa President Thabo Mbeki to mediate between Mr Mugabe and the MDC party.
Over Easter, the country's bishops warned of a mass uprising unless free elections are held, in a letter pinned up in churches.