The Vatican said on Monday (March 15) that priests and other Roman Catholic Church ministers cannot bless same-sex unions.
The ruling was a response to practices in some countries - including the United States and Germany, where parishes and ministers have begun blessing same-sex unions in lieu of marriage, and calls for bishops to defacto institutionalize these.
In response to formal questions from a number of dioceses on whether this practice was allowed, the Vatican's doctrinal office issued the ruling: "Negative."
It said Pope Francis approved the response.
The office note said that since marriage between a man and a woman was a sacrament and blessings are related to the sacrament of marriage, they could not be extended to same-sex couples.
At least two German bishops, including one of the pope's top advisors, have expressed support for some kind of "pastoral" blessing for same-sex unions.
But the note approved by the pope ruled this out.
The Church teaches that gay tendencies are not sinful but gay acts are and that gay people must be treated with respect.
Last year, the Vatican had to move to clarify comments attributed to Pope Francis on civil union laws in a documentary, saying they were taken out of context and did not signal a change in Church doctrine on gay people or support for same-sex marriage.