Catholics and secular groups in Italy will go head to head over government proposals to grant homosexual couples legal status, in demonstrations planned for tomorrow.

The rival protests in Rome come at a time of increasing tension between conservatives and secular groups in the country.

Romano Prodi, the Italian Prime Minister proposed allowing civil unions in February. The planned law, which would also give unmarried heterosexual couples more rights, has met with strong opposition from conservatives and centre-left Catholics in the Italian Parliament.

Several members of Prodi’s own centre-left governing coalition plan to take part in the protest. They include Paola Binetti, a senator and member of the conservative Catholic group Opus Dei, who has been a prominent figure among left-wing Catholics.

Domenico Delle Foglie, protest organiser for the conservative groups said the Unions proposal was “the straw that broke the camel’s back” and “unfair competition” to marriage.

The annual number of marriages in Italy, an overwhelmingly Catholic country, fell from 419,000 in 1972 to 250,000 in 2005. The number of children born to unwed parents has doubled in 10 years.

The Catholic Church has faced accusations of interference in political affairs. It has asked bishops not to protest tomorrow, but encouraged priests, nuns and churchgoers to take part. In a referendum on medically assisted reproduction in 2005, the Vatican and the Italian Church successfully urged voters to stay at home rather than vote.

The Italian Archbishop, Angelo Bagnasco, recently received a bullet and his photograph stamped with a swastika in the post, apparently for his opposition to civil unions.

Franco Garelli, Professor of religious sociology at the University of Turin, said the demonstration did not come at a good time for the Church and said it was facing “a split with civil society” over the issue.