The President of Argentina has said she will become the godmother to the child of a lesbian couple.

The child, Umma Azul, who is just over two months old, is to be baptised with her mothers Carina Villarroel and Soledad Ortiz, in a Catholic cathedral.

Based on an old Russian tradition, couples can ask the president to be godparent to their seventh child.

Azul is the first child of her mothers, and will be the first known to receive the blessing in the country under such circumstances.

Nancy Esteche of the presidential office confirmed that it would make an exception for the couple who married last year.

President Cristina Fernandez won a battle with the Catholic church four years ago and Argentina became the first South American country to legalise same-sex marriage.

Fernandez will not participate in the baptism ceremony which will take place in Cordoba.

Gay rights advocates celebrated the move, in the hope that it signals a shift in the Catholic church.