The Catholic church has denied that the Pope had suggested condoms could be used to avoid pregnancy.

The Vatican's moral watchdog, the Congregation of the Doctrine of the Faith, issued a statement saying some commentators had misunderstood and misrepresented the Pope's remarks in a book-length interview released last month entitled "Light of the World."

The Vatican has been under pressure from conservative theologians to issue such a clarification amid widespread confusion about what the Pope meant and whether he was breaking with church teaching.

In the book, he said that condoms were not the real or moral solution to battling HIV and Aids. But he said that condom use in some cases, such as for male prostitutes, could be a first step in a more moral and responsible human sexuality.

The Vatican statement reaffirmed that the church considered prostitution "gravely immoral."

"However, those involved in prostitution who are HIV positive and who seek to diminish the risk of contagion by the use of a condom may be taking the first step in respecting the life of another even if the evil of prostitution remains in all its gravity," the statement said.

It stressed that his logic was "in full conformity with the moral theological tradition of the church."

The Pope's remarks have been mired in confusion ever since they were first published ahead of the official release date in an excerpt in the Vatican newspaper L'Osservatore Romano on November 20.

The official Italian translation of the original German published in L'Osservatore made two errors that fuelled the confusion: It used the word "justified" in the Pope's analysis and also used the feminine version of 'prostitute' as opposed to the masculine - an important distinction given that condoms in heterosexual intercourse are a form of artificial contraception, which the church opposes.

The Vatican spokesman, the Rev. Federico Lombardi, added to the confusion when he said at the official book presentation on November 23 that he had spoken to the pontiff and asked if it mattered whether the prostitute in question was male or female. Mr Lombardi said the Pope told him no, and that it did not matter if it was a man, woman or transsexual.

In the statement, the Vatican stuck closely to what the pontiff originally said in the interview and stressed that he was not talking about sex between husband and wife or condom use as a means of contraception.

"The idea that anyone could deduce from the words of Benedict XVI that it is somehow legitimate, in certain situations, to use condoms to avoid an unwanted pregnancy is completely arbitrary and is in no way justified either by his words or in his thought," the statement said.