The 6.6-magnitude quake that hit on Sunday morning was the most powerful yet, and although no-one was killed, it destroyed a Benedictine cathedral, a medieval tower and other landmarks in a mountainous region of small historic towns.

Lost or severely damaged in the shaking were ancient Roman walls, Gothic and Baroque churches and centuries-old paintings crushed beneath tons of brick, sandstone and marble.

Italian Premier Matteo Renzi said the nation's "soul is disturbed" by the series of quakes, starting with the deadly August 24 event that killed nearly 300 people.

There were two powerful aftershocks on Wednesday, and then on Sunday the strongest earthquake to hit Italy in 36 years.

The lack of fatalities was attributed to the evacuation of sensitive areas and fragile city centres.

Nearly 8,000 people have been moved to shelters or hotels following the quakes last week and on Sunday, and the Civil Protection agency was expecting the number to reach 11,000 by Monday morning.

Many who stayed behind were sleeping in camper vans or other vehicles, out of harm's way.

Mr Renzi vowed to rebuild houses, churches and business, saying, "a piece of Italian identity is at stake at this moment".

He said: "Feeling the earth collapse beneath your feet is not a metaphorical expression but is what happened this morning, and half of Italy felt this."

The earthquake struck another painful blow to the rich artistic heritage of villages that dot the Apennine Mountains.

The worst damage was reported in Norcia, a town in Umbria closest to the epicentre, with two churches destroyed, including the 14th century Basilica of St Benedict, built on the traditional birthplace of St Benedict, founder of the Benedictine monastic order.

The Cathedral of St Mary Argentea, known for its 15th century frescoes, was also destroyed, with only the cracked facade still standing.

Television images showed nuns rushing into the main piazza as the bell tower appeared on the verge of collapse. Later, nuns and monks knelt in prayer in the main piazza.

A firefighter appealed to a priest to help keep residents calm in an effort to prevent them from looking for loved ones.

Large sections of Norcia's ancient Roman city walls - which suffered damage and cracks in the previous quakes - crumbled, along with towers.

Amatrice, the town that bore the brunt of destruction on August 24, suffered blows to treasures that had withstood the earthquakes of the past weeks.

The community's medieval bell tower stood tall amid the rubble after the August quake, becoming a symbol of hope and resilience for the stricken population.

During a visit to the quake zone earlier this month, Pope Francis prayed alone amid the rubble, the brick tower still standing in the background. But the latest earthquake partially collapsed it. The 15th century Church of Sant'Agostino also fell down.

The quake was felt as far north as Salzburg, Austria, and all the way down the Italian peninsula to the Puglia region, the heel of the boot. In Rome, some 95 miles away, people rushed into the streets in pajamas.

With a preliminary magnitude of 6.6, it was the strongest earthquake since a 6.9 one near Naples killed some 3,000 people on November 23 1980.

Around 20 people suffered mostly minor injuries. The authorities responded with helicopters to help the injured and monitor collapses, as many roads were blocked by landslides.

Seismologists said the shaking came from a series of faults in the Apennines, and they could not rule out more, possibly stronger quakes in the near future.