The Vatican has confirmed that its website suffered a second hacker attack in the space of six days but declined to comment on the event.
"It happened, but we have no comment to make on it," the Vatican spokesman, Father Federico Lombardi, said.
The Anonymous hacker collective claimed responsibility for the attack Monday, which cut off access to the Vatican website www.vatican.va for several hours and violated data on the Vatican Radio computer system.
Anonymous said the incursion into the Vatican Radio system was justified by the fact that the radio's powerful transmitters sited in the countryside outside Rome constituted a health risk to people living in the vicinity.
"Unfortunately it is a well-known fact that you use transmitters with a transmission capacity that greatly exceeds the legal limits, and it is also a sad fact that exposure to electromagnetic waves of high intensity is connected to the development of serious neoplastic diseases such as leukemia and cancer," the group said in a message posted on pastebin.com.
"Anonymous cannot allow these crimes to continue unpunished and we remind you that you are 'guests' on Italian soil," the statement said. "We would like to see tangible signs that you are showing an interest in these matters, perhaps by modifying the location and the power of some of your transmission equipment."
The earlier attack March 7 also cut off access to the Vatican website for several hours and disabled internal mail servers.
Anonymous justified that action by citing the Vatican's role in helping Nazi war criminals to evade international justice, the destruction of books of immense historic value and the sexual molestation of children by members of the clergy.
The attack on the Vatican was preceded over the weekend by similar attacks on Italy's national tax collecting agency, Equitalia, and the national railway company, Trenitalia.
The latest Anonymous statement referred to a "pathetic report" by the California-based digital security company Imperva, which described an earlier attack on the Vatican, in August 2011, as a "failure." The attack reportedly took place while Pope Benedict XVI was in Spain for World Youth Day celebrations.
Anonymous said Imperva's report was based on information that was readily accessible to anyone familiar with the Web and it had been a mistake on the part of the Vatican to make its contents public.