For the first time in 80 years the Vatican will from tomorrow stop automatically adopting Italian laws because of potential “anti-Catholic” legislation.

Amid fears of new laws on euthanasia and gay marriage, the Vatican’s legal chief said that the rupture was due to growing contrast between Italian civil legislation and ”the irreversible principles of the Church”.

According to the L’Osservatore Romano, the Vatican daily, Monsignor Jose’ Maria Serrano Ruiz, head of the Vatican State Court of Appeal and president of the Commission for the Revision of the Code of Vatican Law, said the move was also motivated by the ”exorbitant number” of Italian laws, as well as their ”instability”.

It also however had to do with the growing contrast between Italian civil legislation and ''the irreversible principles of the Church'', Monsignor Serrano Ruiz said. Under the Lateran Treaty of 1929 between Italy and the Vatican, signed by the then Fascist dictator Benito Mussolini and Cardinal Pietro Gasparri, the Vatican Secretary of State, Italian laws are automatically incorporated into the Vatican legal code.

However the Treaty allowed for exceptions in cases where there was “radical incompatibility” with the basic principles of canon law, Monsignor Serrano Ruiz said.

Until now this had rarely been applied. But under a new Vatican statute which was signed in October by Pope Benedict XVI and comes into force on 1 January 2009, all Italian laws would be closely examined by the Vatican from now on before being adopted as part of the Holy See’s own legislation.

Elio Vito, the Italian Minister for Relations with Parliament, said he agreed that ”from a technical point of view” the Italian Parliament adopted too many laws, which were “often written badly and sometimes not very understandable”.

But he pointed out that the centre Right government of Silvio Berlusconi, which came to power in May, had a Minister for Simplification whose job was to eliminate over 36,000 laws from the statute books.

Marco Politi, a leading Vatican expert, said the true cause of Vatican alarm was not only “liberal” Italan laws on divorce and abortion but also a “trend in European legislation” which “sooner or later” could lead to the introduction of laws in Italy relaxing the ban on euthanasia or sanctioning “civil unions” between homosexuals. “What would happen if, say, a Vatican resident - man or women - asked for the legal right to live with his or her partner?” Mr Politi said.

However Giorgo Tonini, a centre Left senator and former head of the Italian Federation of Catholic Universities, said although Parliament produced laws “based on the changeable course of public opinion”, it was “understandable” for the Vatican, which was a sovereign state, to “distance itself” from social legislation which it regarded as “amoral”.

Giovanni Maria Vian, the editor of L’Osservatore Romano, said it was “a matter of common sense.”

Roberto Calderoli, the Minister for Simplication, said the Berlusconi government had no plans for any laws “which go against the values of the Church”. He said it would have been more appropriate if the Vatican had taken a stricter legal stand during the previous centre Left government of Romano Prodi, which had considered a law giving “civil unions” between homosexuals legal status.

The Vatican’s new statute also says the Holy See will in future scrutinise international treaties before deciding whether to give them “explicit” approval. This follows Vatican objections to a French EU proposal for a United Nations declaration decriminalising homosexuality, which was backed by Italy but which the Vatican said placed “different sexual orientations on the same level” and would encourage laws allowing gay marriage.

There were gay rights protests when in his end of year address to the Curia Pope Benedict said homosexuality threatened humanity as much as the destruction of the rainforests, and that “blurring” gender could endanger the human race by “destroying God’s work”. However, Cardinal Cormac Murphy-O’Connor, the Archbishop of Westminster, said the Pope was only trying to emphasise the importance of the family and the responsibility of humans to procreate, and his comments had been “misrepresented”.