Graffiti speaking out against Roman Catholic head Pope Benedict, including one reading "Death to Ratzinger", has been found on walls in Naples ahead of a scheduled visit there by the Pontiff later this month.

A source in Italy's anti-terrorist police said they suspected the graffiti was the work of leftist and anarchist groups, but investigations were still ongoing.

Graffiti against the Pope as well as Archbishop Angelo Bagnasco, head of the Italian Bishops Conference, also appeared in a number of Italian cities earlier this year after Archbishop Bagnasco made comments that angered the Italian gay community.

The Pope, the former Cardinal Joseph Ratzinger, is due to make a one-day visit to the largest city in southern Italy on 21 October to open an inter-religious meeting.