Two professors from American religious universities claim they have evidence to show that sexual orientation can be changed.

Mark Yarhouse of Regent University and Stanton Jones at Wheaton College say that almost a quarter of the people they studied over six to seven years were able to become straight.

The study results have been contested by other academics, who say that while behaviour may change, sexual orientation remains the same.

Yarhouse and Jones followed 98 patients who attended Exodus Ministries, which claims that “any individual can experience freedom [from homosexuality] through the support of caring individuals and the healing power of Jesus Christ”.

According to CNN, 35 of those on the programme dropped out, with some claiming they were cured of all “homosexual inclinations”. One remained gay, the study said.

Of the 65 remaining, 23 per cent were said to have become heterosexual. Thirty per cent became celibate, which the authors said was evidence of a reduction in homosexuality.

“The findings of this study appear to contradict the commonly expressed view that sexual orientation is not changeable,” the authors wrote.

Yarhouse told CNN: “I’d like to see mental health organisations to show greater respect for diversity for how a person chooses to live their life and live this out.”

But other experts dismissed the findings. Eli Coleman, professor and director of Human Sexuality at the University of Minnesota Medical School, said: “We’ve been through this over and over. You can get behavioral changes, but that’s not orientation change. You can get short-term behavioural change. It’s not sustained.”

Dr Jack Drescher, an associate professor of psychiatry at New York Medical College, said the study was at odds with the bulk of research on the topic.

He said: “I think the authors have a bias and I have a bias. Everybody has a bias. That’s why we have accumulation of data – and that doesn’t support their data.”