A leading member of the governing Socialist party in Spain has attacked the Roman Catholic Church for getting involved in politics.

On Sunday a “family” rally was held in Madrid, and senior church figures lined up to criticise laws introduced since the Socialists took power in 2004, including same-sex marriage.

Pope Benedict XVI addressed the crowd, estimated at 150,000 people, by a videolink from Rome.

The main opposition party, the rightwing Popular Party, supported the protest march.

The secretary of the Partido Socialista Obrero Español’s federal executive is demanding that the Church retract accusations by the Archbishop of Valencia that the government was promoting “radical secularism” that would lead to the breakdown of democracy.

The Archbishop of Mardid went further, claiming that the government’s family policy was a retrograde step for human rights.

José Blanco told El Pais newspaper that the comments by religious leaders were a “political act.”

Spaniards are set to go to the polls in a general election in March.

“We will stand up to this offensive by the ecclesiastical hierarchy, which constitutes the first act of the PP’s election campaign,” Mr Blanco said, accusing the Roman Catholic hierarchy of attacking the democratic institutions of the country.

The Pope told the crowd that the family is “based on the unbreakable union of man and woman and represents the privileged environment where human life is welcomed and protected from the beginning to its natural end.”

Benedict has consistently used family values arguments to oppose gay equality.

In July 2006 his views about gay marriage brought him into conflict with the secular Spanish Prime Minister Jose Luis Rodriguez Zapatero.

A senior Vatican source revealed that Mr Zapatero, who brought in Spain’s gay marriage laws, refused to attend a Mass said by the Pope.

Whether the Church’s stance will have an effect on the elections is unclear, but the race is expected to be close.

An Ipsos Expansion opinion poll conducted last month put the Socialists on 41.3% and the PP on 38%.

The 350 members of the Congress of Deputies and the 208 directly-elected Senators will go be chosen on 9th March.