Around 200 African bishops, along with dozens of other bishops and Africa experts, also accused multinational companies in Africa of "crimes against humanity" and urged Africans to beware of "surreptitious" attempts by international organizations to destroy traditional African values.
Their three-week synod, which ends formally on Sunday with a mass by Pope Benedict, covered a range of Africa's problems, such as AIDS, corruption, poverty, development aspirations and crime.
But it had a very direct message for corrupt African leaders who were raised Catholics.
"Many Catholics in high office have fallen woefully short in their performance in office. The synod calls on such people to repent, or quit the public arena and stop causing havoc to the people and giving the Catholic Church a bad name."
The message did not name any leaders.
The international community has for years called on Robert Mugabe of Zimbabwe, who was raised a Catholic and educated by Jesuits, to step down, saying he had brought his once-prosperous country to its knees.
Another African leader who was raised a Catholic and has been accused of corruption is Angola's President Eduardo dos Santos. Both men deny any wrongdoing.
Rights groups and international agencies have accused Angola's government of siphoning away billions in oil revenue and urged it to improve transparency.
Angola rivals Nigeria as Africa's biggest oil producer but about two thirds of the population live on less than $2 a day. It ranks 158th on Transparency International's 180-nation list, in which the country perceived as most corrupt is in last place.
The synod bishops hit out forcefully at multinational companies, saying they were one of Africa's greatest problems.
"Multinationals have to stop their criminal devastation of the environment in their greedy exploitation of natural resources," the bishops said.
"It is short-sighted policy to foment wars in order to make fast gains from chaos, at the cost of human lives and blood. Is there no-one out there able and willing to stop all these crimes against humanity?"
The message said that whatever the faults of foreigners, the complicity of African leaders blinded by greed for power and money was a blight on entire populations and nations.
It condemned "the shameful and tragic collusion of the local leaders: politicians who betray and sell out their nations, dirty business people who collude with rapacious multinationals, African arms dealers and traffickers who thrive on small arms that cause great havoc on human lives..."
In a section on AIDS, the bishops' message repeated the Church position that the spread of the disease could not be stopped by the use of condoms alone.
Last March, on his way to his first trip to Africa, the pope caused an international storm by saying that the use of condoms could actually worsen the spread of AIDS.
The Church teaches that pre-marital abstinence and fidelity within heterosexual marriage are the best ways to prevent the spread of AIDS.
The bishops said the developed world had to treat Africa with respect and strive to remove "unjust structures piled heavily against her."
It said African nations must "carefully scrutinize" programs offered by the international community to spot "surreptitious attempts to destroy and undermine the precious African values of family and human life."