Anti-terrorism measures ahead of Vatican's Easter ceremonies.

Italian and Vatican security officials have outlined plans for the rapid evacuation of St Peter's Square in the event of a terrorist attack, according to a report in Italian daily newspaper Corriere della Sera.

The plan comes at a time of growing instability in Libya as well as a warning from Italy's security services of the increased possibility of terrorist attacks and infiltration from the Balkans.

Authorities first tested the plan following the weekly papal audience on 2 March when the barriers around St Peter's Square were opened after remaining closed for years. Under the guard of numerous police officers, the barrier-free colonnade facilitated the quick exit of about 30,000 pilgrims, decongesting a normally slow and crowded process.

Everyone attending the Wednesday morning papal audiences in St Peter's Square must have booked tickets and there are security checks for entry into the square. There are also permanent security checks for entry into St Peter's Basilica and therefore for the Holy Door.

However on other days and for the Sunday Angelus the square is open to all.

The joint security plan comes during the Vatican's ongoing Jubilee Year of Mercy which, aside from the recent exposition of the relics of St Pio, is so far is not attracting the large crowds initially expected.