A priest in Italy on Sunday blessed the marriage of a 64-year-old transsexual to her 58-year-old male partner, in defiance of Vatican guidelines, the ANSA news agency reported.

Sandra Alvino -- who underwent a sex change more than 30 years ago -- and Fortunato Talotta had been in a civil partnership for 25 years before tying the knot in a religious ceremony in Piagge, an industrial suburb of Florence.

I do not understand how something like that can be done. It's against nature and it does not bring anything to the church.

Cardinal Renato Martino

Father Alessandro Santoro gave his blessing to the marriage, which was attended by some 200 people, despite the Roman Catholic Church advising him not to go ahead with it.

Santoro defended his decision, saying it was "not an act of rebellion," but rather "an act of loyalty to my congregation, to the church and to the people that I love. It was my duty".

Former Florence archbishop Cardinal Ennio Antonelli had blocked an attempt by Alvino and Talotta to marry two years ago, and his successor Giuseppe Betori later also asked Santoro not to bless their union, ANSA reported.

Cardinal Renato Martino, a senior Vatican official, strongly criticised Santoro's decision to wed the couple.

"I do not understand how something like that can be done. It's against nature and it does not bring anything to the church," which does not recognise same-sex partnerships.

"Biology, that God made man and woman, cannot be changed by trickery," he sai