An evangelical church is marketing olive oil as a cure-all treatment for everything from schizophrenia to relationship problems.

The Universal Church of the Kingdom of God is holding an event this Sunday, which is being pitched as "the unique opportunity for those of you in need of a miracle".

Through a mass mail drop in Auckland, the church is promoting "holy oil", olive oil that has been blessed at the sites of biblical miracles in Israel. It is reportedly a cure for mental illness, stomach and bladder problems and even relationship difficulties.

The UCKG originated in Brazil, where it has 5,000 churches, but arrived in New Zealand in 2005. It has previously claimed it can heal HIV, homosexuality and depression.

According to Forbes, the founder of the church, Edir Macedo, is a billionaire and reportedly bought a stake in a Brazilian bank in 2013.

In an email to the New Zealand Herald, Bishop Victor Silva played down the effects of the oil, saying it could not actually cure illness. Instead, he said using it was an act of faith which could help in the restorative process.

The statement read: "Concerning the oil, we don't claim it has healing powers but we believe that faith in God does. Anointing with oil is an act of faith.

"The church does not have specialist medical expertise so people who present themselves at church with an illness are always advised to seek a medical diagnosis from their GP.

"Furthermore, anyone claiming to have been healed whilst attending a [church] service is invariably referred to their doctor because the [church] only recognises healings that have been confirmed by a qualified medical practitioner."

Yet the eight-page newsletter stated the oil had helped cure people of ailments, where doctors and medicine had not been successful.

It read: "The Holy Oil was chosen by God as an instrument of faith to heal the sick. Learn how to use it to annoint the sick, the emotionally depressed, your loved ones and family, your workplace and objects that represent difficulties or challenges in your life."

The newsletter also included a series of case studies. One church member claimed it helped cure a pancreatic tumour: "After anointing herself for a period of time with the oil, she went back to the doctors for a check-up. The doctors couldn't find anything! No trace of the tumour was detected."

Other ailments supposedly cured with the oil were schizophrenia, a heart defect in a 3-year-old boy, low iron, skin conditions and bladder problems. The newsletter even claimed marriages could be saved.

In small print, it offered the disclaimer: "The UCKG Help Centre does not claim to heal people but believes that God can through the power of faith. Always follow your doctor's instructions."