The Vatican is objecting to a law that would criminalise violence and hate speech against gay and transgender people in Italy.

The Holy See has sent an "unprecedented" diplomatic protest to the government claiming the bill would be an attack on freedom of expression and that it is unnecessary because existing laws already condemn homophobia.

The bill, which would punish acts of discrimination and incitement to violence against gay, lesbian, transgender and disabled people, was approved by Italy's lower house of Parliament in November.

The Telegraph says that the Vatican fears that if it passes into law, it could lead to the Catholic Church in Italy being prosecuted for refusing to conduct gay marriages, for opposing adoption by gay couples through Catholic institutions or for refusing to teach gender theory in Catholic schools.

The Italian Bishops' Conference has already protested against the bill and Cesare Mirabelli, a former President of Italy's constitutional court, told Vatican News that it would put fundamental principles such as freedom of thought and speech at risk.

But writing on Twitter, Alessandro Zan, the MP pushing the bill, said the Vatican's concerns were unfounded:

"The bill does not restrict in any way freedom of expression or religious freedom....all the concerns and doubts will be listened to, but there cannot be any foreign interference in the workings of a sovereign parliament."