The ACP accused Senator Mullen of a “a gratuitous and ill-informed attack on Fr Flannery”.

Senator Mullen suggested that Fr Flannery had expressed views that were at variance with the fundamental teachings of the Catholic Church.

In 2012, Fr Flannery was silenced by the Vatican’s Congregation for the Doctrine of the Faith (CDF) over articles he had written in Reality, the Redemptorist’s magazine.

He went on to say that Fr Flannery made it “impossible for anyone to deal with him because he wants it completely his own way.

“I get the impression, even from talking to people within the Redemptorist order, that Fr Tony has made it hard on himself, that’s he’s a difficult man. He doesn’t appear to be able to work through the difficulties, but maybe I’m doing him an injustice.”

In a statement from the ACP Fr Brendan Hoban said suggestions that Fr Flannery is a difficult man are “unwarranted and unfair.”

He pointed out that Senator Mullen had admitted himself that he was “out of his depth theologically” in dealing with the issues involved. “I think he should now accept that his remarks were at the very least inaccurate and incoherent and should be withdrawn.”

During a discussion on The Sean Moncrieff Show, Senator Mullen was asked how he felt about the expulsion of Fr Flannery from the priesthood.

He responded: “I don’t sympathise with a view that a priest can have whatever theological views they want and expect to continue on in their job as if the church had no right to try and keep the integrity of what it proposes to the world.

“He expressed his views about the institution of the priest and the Last Supper for instance. It is legitimate that there is a role within the Catholic Church that there is a set of teachings that the Church believes to be true. It doesn’t matter if you are ordained. That doesn’t give you special rights.”

Senator Mullen admitted to Moncrieff he did not regard himself as qualified to speak on theological matters but “he (Fr Flannery) appeared to write that the priesthood as we understand it was not necessarily constituted by Christ at the Last Supper.”

The ACP said this was incorrect and that Fr Flannery had actually stated: “I do not accept that the priesthood as we have it now is as Christ intended.”

Senator Mullen stated that the Congregation of the Doctrine of the Faith (CDF) had a right to uphold Catholic doctrine and to stop priests who held contrary views from teaching or preaching. “That’s normal management of the organisation’s mission.”

The ACP responded by stating that Senator Mullen seemed to suggest Fr Flannery had a problem with the role of the CDF.

“Anyone who has followed this case will know that time and again Tony Flannery has made it clear that the difficulty is not with the role of the CDF but with the way the process of investigation has been carried out.”