The Temple of Venus and walls of a tomb and shop in the long-neglected ruins of Pompeii near Naples have been damaged, possibly due to heavy rain, officials said on Monday.

Custodians at the site found that a two-meter wall of an ancient shop in the ruined city - which had recently been restored - had collapsed under the weight of another wall that crumbled onto it.

It followed the discovery Sunday that parts of an archway in the temple had fallen off and a wall in the necropolis - the biggest in the ancient Roman city - had tumbled down.

The areas affected have been closed to the public.

Italian Culture Minister Dario Franceschini has called a meeting this week to assess the damage and progress made in an EU-backed project to restore the archaeological site.

"The news of these collapses comes at a time in which there is an unprecedented vacuum in the management of Pompeii," said Antonio Irlando from the Cultural Heritage Observatory, a non-governmental group that follows work on Pompeii.

The project is seen as crucial to the survival of Pompeii after a series of collapses at the site in the shadow of Mount Vesuvius - the volcano that quickly covered the city in layers of ash in AD 79.