The British-inspired atheist bus poster campaign today (Tuesday) moved closer to the Vatican after the Italian Union of Rationalist Atheists and Agnostics (UAAR) said slogans proclaiming that God does not exist would appear from next month (February) on buses in Genoa.

Father Gianfranco Celabrese, a spokesman for Cardinal Angelo Bagnasco, the Archbishop of Genoa and head of the Italian Bishops Conference, attacked the atheist campaign, saying it amounted to "intolerance". Vatican officials were said to be alarmed at reports that the atheist campaign would target Rome next.

Father Calabrese said: "There are some methods which promote dialogue and others which feed intolerance. Head-on opposition always demonstrates intolerance." The Genoa bus campaign will use the slogan: "The bad news is that God does not exist. The good news is that we do not need him", rather than the claim by campaigners in Britain and Spain that God "probably" does not exist.

The UAAR said it had chosen Genoa deliberately in order to challenge Roman Catholic beliefs "on Bagnasco's own turf." Cardinal Bagnasco, who is close to Pope Benedict XVI, is an outspoken opponent of artificial insemination and gay marriage, and last June opposed a Gay Pride march in Genoa staged on the same day as the feast of Corpus Domini.

Raffaele Carcano, head of UAAR, said the Genoa campaign was "not a provocation" but an attempt to link the concept of "living without faith" to Italy's secular rather than Catholic traditions. It was partly aimed at "the positions taken by the Church on civil rights, reproduction and scientific research".

Mr Carcano said the Genoa campaign cost of 7000 Euros was being paid for by donations. "Who knows, at this rate we will be able next to put the slogans on buses in Rome which pass close to the Vatican" he said.

Father Calabrese said Cardinal Bagnasco, who is leading a group of seminarians from Genoa on a pilgrimage to the Marian shrine at Fatima in Portugal, would make a statement when he returned. However Father Marco Granara, Rector of the Sanctuary of Madonna della Guardia near Genoa, Liguria's most important Marian shrine, said the atheist campaign could "act as a stimulus for Christians to offer their own witness to faith in an intelligent way".

Marta Vincenzi, the mayor of Genoa, said the city authorities could not "act as censors". The campaign might in any case rebound on the atheists, she said, "since they are saying after all that the idea that God does not exist is bad news". She hoped the campaign would be seen as an invitation to debate, and would "not offend anyone. If passengers do not want to travel on one of the atheist buses, they can always wait for the next one" Ms Vincenzi said.

Bruno Sessarego, head of the Genoa public transport company AMT, said it had seen no reason not to sign the contract for the bus advertisements, since the law allowed any advertisement which was not "obscene or offensive".