The Vatican has said that priests cannot bless same-sex unions and that such blessings are not valid

The Catholic Church does not have the power to bless same-sex unions, the Vatican office responsible for doctrine said on March 15, according to the BBC.

It is "impossible" for God to "bless sin", the Congregation for the Doctrine of the Faith (CDF) noted. 

But the CDF did note the “positive elements” in same-sex relationships.

The BBC says Pope Francis has approved the response by the CDF, saying it was “not intended to be a form of unjust discrimination, but rather a reminder of the truth of the liturgical rite.”

The CDF's response was in answer to the question posed to it: “Does the Church have the power to give the blessing to unions of persons of the same sex?”  It replied: "Negative".

The CDF noted that marriage between a man and a woman is sacrament and therefore blessings cannot be extended to same-sex couples.

In the Catholic Church, a blessing is given by a priest or other minister in the name of the Church. 

Some parishes in recent months, including in Germany and the United States, have started giving blessings to people in same-sex relationships as a way to welcome gay Catholics to the church, Reuters news agency reported.

The Catholic Church have expressed alarm over these practices, particularly those in Germany where at least two bishops, including Cardinal Reinhard Marx of Munich, one of the pope’s top advisers, have shown support for some kind of “pastoral” blessing.

Churches in Africa and Asia also strongly oppose gay marriage. Conservatives have warned that debates on homosexuality have spawned debilitating divisions in other Christian Churches, such as the Anglican communion, according to Reuters.