A community of nuns in Spain who have split with the Vatican because of a property dispute confirmed Friday their "irreversible" desire to leave the Church, paving the way for their excommunication.

The 16 Poor Clare sisters who live in a 15th century convent in the northern town of Belorado near Burgos said they were breaking away from the Roman Catholic Church because it had blocked their attempt to buy another convent.

They also accused the Vatican of "doctrinal chaos" and "contradictions" in its positions on matters of faith in their May 13 letter announcing the split, which was published on social media and signed by the order's Mother Superior, Sister Isabel de la Trinidad.

The nuns announced they were now under the jurisdiction of excommunicated priest Pablo de Rojas Sanchez-Franco, who is known for his ultraconservative views.

He heads the Devout Union of the Apostle Saint Paul, a religious group regarded as a sect by the Catholic Church and presents himself as a bishop, appearing in public in episcopal robes.

Sanchez-Franco backs sedevacantism, a movement which holds that all popes since Pius XII, who died in 1958, are heretics and that there is currently no valid pontiff.

The Archbishop of Burgos, Mario Iceta who in 2019 excommunicated Sanchez-Franco, has expressed "perplexity" over the nuns' breakaway.

The Church had given the rebel nuns until Friday to appear before an ecclesiastical tribunal to confirm their decision to split, which could lead to excommunication -- a move that would deprive them of certain sacraments such as confession.

The nuns did not appear before the tribunal but instead said in a statement on Friday they had sent a fax to the archbishop's office in which "we have made known our unanimous and irreversible wish" to leave the Church.

This decision is "the fruit of mature, meditative and conscious reflection, which has been validated by all" the nuns of the community, they added in the statement posted on their recently created Instagram account, saying that they were acting "freely and voluntarily".

The nuns said they did not recognise the tribunal and called the proceedings against them a "farce".

"He who truly loves God does not truly love if he does not have the ardent and constant desire to suffer for his sake," they wrote.

Church officials have so far not reacted publicly to the statement.