An agency contracted to carry DNA testing for children believed to have been sired by Catholic priests wants the report made public in 30 days.
An International Catholic Organisation hired DNA Testing Services, formerly known as CSI Nairobi, to do the paternity tests.
The firm's director, Kinyanjui Murigi, said the campaign began on Saturday. The agency will then send the samples to their parent company in the US for testing.
"The cases are unique. In some cases, some children have called and claimed their fathers were priests, but they are dead. In other cases, some church officials have babies with married men."
Kinyanjui spoke to the Star during an interview on the phone on Thursday.
"The final decision depends on the principal (client) who has subsidised the project. We can't disclose the name because that will jeopardise the investigations," he said.
Pope apologises
The Catholic Church across the world has been hit by sex scandals. On Sunday, the head of the Catholic Church, Pope Francis, apologised to thousands of people gathered at Phoenix Park in Dublin, Ireland, to protest against sexual abuse by priests.
"We ask forgiveness for the abuses in Ireland," CNN quoted the Pope at the Mass.
He listed a litany of abuses including clerical sex crimes, a lack of compassion and action by church leaders and the separation of single mothers and children in industrial laundries.
In Kenya, several children, mothers and families have accused Catholic priests of siring and abandoning children. Some have been taken to court.
In May this year, a Kitui court summoned several witnesses in a case against a Catholic priest who allegedly impregnated a student and attempted to kill her.
Father Japheth Kimanzi is also accused of assaulting and causing grievous harm to the girl. He allegedly attempted to cover-up infidelity yet he took celibacy vows.
DNA testing
"When a person seeks a DNA test, we take the sample and also write to the church to send for the official involved. The church has co-operated," Kinyanjui said.
"The group wants us to give every child and mother a chance if they have sired a child with the priests. It is a straightforward activity."
He said the results will be sent to the priest, the mother, the church and the Vatican.
"We are not targeting anybody, and we are not sure the number of people who will come up," he said.
Kinyanjui said the 30-day campaign will end on September 24.