The Home Secretary Theresa May is being urged to step in to prevent a Nigerian “witch hunter” returning to the UK after she flew in to preach to congregations in London.

“Lady Apostle” Helen Ukpabio, founder of the controversial Liberty Foundation Gospel Ministries, is believed to still be in the capital after addressing three gatherings last week.

The born-again Christian Pentecostal preacher claims to have been betrothed to Satan as a teenager before being rescued from a cult at the age of 17. She now specialises in liberating captives in “deliverance sessions” that critics claim are little more than crude exorcisms.

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Among her advice to parents is the suggestion: “If a child under the age of two screams in the night, cries and is always feverish with deteriorating health, he or she is a servant of Satan.”

Campaigners say such beliefs, prevalent in some parts of the developing world, can put children’s safety at risk. They have written to Ms May to urge that the pastor be banned from the UK after the current tour.

In the letter, the Witchcraft and Human Rights Information Network (WHRIN), the Bar Human Rights Committee of England and Wales and the International Humanist and Ethical Union (IHEU) cite the cases of Victoria Climbié and Kristy Bamu as examples where witchcraft beliefs played a role in the horrific torture and murder of children.

“Whilst the Government has moved swiftly to block entry to the UK for Islamic preachers whose presence is considered as harmful to the public good, there have been no cases of Christian pastors facing such measures,” the letter said. Ms Ukpabio cancelled her first service in south-east London last week after the location was leaked. She is understood to have made three other appearances, including one at a private home.

Around a dozen people attended each event which offered help to those “under attack” from witchcraft, ancestral or “mermaid” spirits.

Bob Churchill, of the IHEU, said: “It is important that the UK authorities send a message to the world that branding children, or anyone, as a witch is beyond the pale.”

Ms Ukpabio founded the church in 1992 in Calabar, Nigeria. It now claims to have 150 branches worldwide.

Gary Foxcroft, of the WHRIN, who has worked extensively in documenting examples of witchcraft abuse, said Ms Ukpabio was one of a number of preachers who regularly travelled to the UK. “The fundamental problem is that churches need to be regulated. Anyone can set up a church tomorrow in their own garden shed with no commitment to child protection or making their accounts transparent or any theological training.”