Cardinal Keith O’Brien allegedly had a long-standing physical relationship with one of the men whose complaints about his conduct sparked his resignation, it is claimed.

Scotland’s Herald newspaper reports the individual left the Catholic priesthood in the middle of the last decade but rejoined and is living on the continent in a post Cardinal O’Brien helped him secure.

The complainant is known to have been in regular telephone contact with Cardinal O’Brien until recently and was a frequent visitor to St Benets, his official residence in Edinburgh.

According to the Herald, the cardinal confessed to the relationship after it was recently revealed there had been several complaints to the Vatican about his sexual behaviour towards priests in the 1980s.

The 75-year-old, who contested the first set of allegations, resigned as leader of the Scottish Catholic Church in late February.

In March, he admitted that his “sexual conduct” had been “below the standards expected” of him.

Earlier this week, it was claimed Cardinal O’Brien groped a priest on the same day he became a cardinal in 2003.

The Scottish priest, now based in London, reportedly made his complaint to the Vatican’s Congregation of Bishops last September.

A Vatican inquiry into Cardinal O’Brien’s sexual conduct is currently taking place.

The cardinal’s outspoken opposition to gay rights is said to have spurred his critics to go public with their allegations.

His remarks, such as describing homosexuality as a “moral degradation”, were a tipping point for several previously close to him, the Herald claims.

In 2012, he stated that same-sex relationships were “harmful to the physical, mental and spiritual wellbeing” and compared equal marriage to slavery and child abuse.

A Catholic Church spokesman said: “Some clergy were not in favour of church efforts to persuade the Scottish Government against same-sex marriage.

“It is also the case that objections were raised to Cardinal O’Brien’s robust rhetoric.

“A number of complaints about Cardinal O’Brien were passed directly to the Vatican. Whether they were precipitated by his comments on homosexuality is not known, since the detail and nature of the complaints were not shared with the Bishops’ Conference of Scotland.”