In a typical Vatican clarification that left both conservatives and progressives convinced they were correct, a spokesman, Federico Lombardi, said that the Pope did mean to say that someone with AIDS should use condoms to prevent infection, whether ''man or woman or transsexual''.

But he said the Pope's ''reasoning certainly cannot be defined as a revolutionary shift'', that he still taught abstinence and fidelity as better than condoms, which were ''not a real or moral solution''.

The stunning U-turn on condoms - traditional Catholic teaching says it is always sinful to use condoms within marriage because it blocks the transmission of life - emerged in interviews with a German journalist published in a book this week. But because Pope Benedict used the example of a male prostitute, conservative Catholics denied that it applied outside homosexual sex. However, in Italian the example was of a female prostitute.

Father Lombardi said because of the confusion he asked the Pope to clarify. The Pope told him the critical point was for someone with AIDS to take ''into consideration the life of another with whom you have a relationship''.

He said several moral theologians had held similar positions - without saying they had been ruthlessly silenced - ''however it is true that until now we had not heard them expressed with such clarity from the mouth of a pope''.

On Monday, the Bishop of Paramatta, Anthony Fisher, a bioethics specialist, released a statement insisting that ''despite some misinterpretation in the international media, the Pope has not deviated from or altered in any way Catholic teaching on the wrongness of contraception''. The Archbishop of Sydney, Cardinal George Pell, also released a statement endorsing Bishop Fisher.

Neither was available for comment yesterday, but conservatives were still unimpressed by the apparent clarification. The bioethicist Nicholas Tonti-Filippini, from the John Paul II Institute for Marriage and Family, said the Pope maintained condoms were not the solution because of their failure rate.

''If you have AIDS it's irresponsible to have sex with anyone, full stop. It's not an act of love to put someone's life at risk.''

Dr Tonti-Filippini said there had been considerable discussion within the church about whether sex within marriage using a condom was still the ''marriage act''. If it was, then the use of condoms to prevent infection would be allowable.

''But others, including the Pope, have said that is not the marriage act. It's like mutual masturbation if you use a condom.''