The Catholic church urged Spaniards to vote for political
parties that do not negotiate with violent Basque separatists ETA -
a direct swipe at the policies of the ruling Socialists.
The Church also spoke out against the legalisation of gay marriage and the reduced importance of religion in the school curriculum, both reforms carried out by the Socialist government.
"Not all the parties and manifestos are equally compatible with the faith and Christian life," the Catholic Church's governing body in Spain said in a statement, without specifically naming parties, aimed at encouraging people to vote "responsibly".
The PSOE Socialist party hit back, calling the Church out of touch with Spanish society and pointing out all Spain's premiers had negotiated with ETA, including former conservative prime minister Jose Maria Aznar.
"If you shouldn't vote for parties that have talked to ETA, you shouldn't vote for anyone, because no party fulfils this requirement," the party said in a statement.
The government ended peace talks after less than a year in 2006 when ETA, which wants independence for Basque territories in Spain and France, bombed a carpark at Madrid airport, killing two people.
Spain's Prime Minister Jose Luis Rodriguez Zapatero has ruled out any chance of returning to the negotiating table with ETA if he wins general elections on March 9.
The spat further strains relations between the ruling PSOE party and the Catholic Church.
The Socialists accused the Church of campaigning for the
conservative opposition after bishops slammed laws on divorce and
abortion at a mass rally in December.
Spain has become notably less Catholic since the death of dictator General Francisco Franco in 1975, who the church supported for much of his rule.
After the return of democracy, church attendance has fallen and attitudes to sex and marriage have become more liberal.