Argentina’s highest-ranking Catholic prelate has warned that the country’s gay marriage bill is a “machination” of the devil.

Cardinal Jorge Bergoglio has called on priests in Buenos Aires, where he is archbishop, to protest against the bill, which is progressing through Argentina’s parliament.

In a letter to the monasteries of Buenos Aires, he wrote: “Let’s not be naive, we’re not talking about a simple political battle; it is a destructive pretension against the plan of God.

“We are not talking about a mere bill, but rather a machination of the Father of Lies that seeks to confuse and deceive the children of God.”

The AFA reports that Cardinal Bergoglio asked parish clergy to read out declarations of the “true” definition of marriage and also claimed that gay adoption was a form of discrimination against children.

However, Argentinian president Cristina Fernandez de Kirchner, who supports the legislation, said the church’s tone was reminiscent of “medieval times and the Inquisition.”

“It is disturbing to hear phrases like war of God or the devil’s projects, which are things that take us back to medieval times and the Inquisition,” she told reporters during an official visit to China.

Mexico City passed a law legalised gay marriage recently, but if Argentina’s bill becomes law, it will be the first country in Latin America to legalise the practice. The bill also proposes giving gay couples the right to adopt.

It recently passed the lower house by 125 votes to 109 and it will now go to senators for approval, before being signed into law by Ms Fernandez de Kirchner.

Currently, only a few areas of Argentina recognise civil unions between same-sex couples: Buenos Aires itself, the province of Río Negro in Patagonia, and the city of Villa Carlos Paz in Córdoba province.

Since the 2002 decision to allow civil unions, Buenos Aires has become one of the hotspots on the international gay-friendly tourist circuit.