A private letter to Pope Francis, which voices concerns among the cardinals over the procedures demonstrated at this year’s Synod of Bishops, has been leaked.

As AFP reports, the letter, which was signed by 13 cardinals and was delivered to the Pope by Australian Cardinal George Pell, takes the leader of the Holy See to task for his perceived liberal biases.

The letter, sent to Francis on Oct. 5, finds fault with papal procedures that were put in place for the three-week global synod, charging that the procedures have been "designed to facilitate predetermined results" regarding disputed questions within the church.

The private note was made public on Monday by Sandro Magister, an Italian journalist who specializes in religious news and who has been critical of Francis in the past.

The letter reads that “various fathers have expressed concern that a synod designed to address a vital pastoral matter -- reinforcing the dignity of marriage and family -- may become dominated by the theological/doctrinal issue of Communion for the divorced and civilly remarried.”

German Cardinal Gerhard Ludwig Muller wants those responsible for giving the private letter to Magister to be brought forward, saying, "This is a new 'Vatileaks.' A private letter belonging to the Pope. How is it possible that it was published?"

Muller was referring to a 2012 incident in which Pope Benedict XVI's butler orchestrated a series of leaks that embarrassed the church.

Muller has been critical of the Pope’s speeches in the past. As The New York Times reports, the cardinal expressed concern over the way the Pope brought up topics of sex and marriage at the Unites Nations recently, saying, “If the pope speaks about social justice, everybody will embrace him, no? It’s not so difficult. But to speak about moral values, and the field of sexuality and matrimony and abortion and these values, is more conflictive.”