Rome  - At least 27 people were reported dead - amid fears of that number rising considerably - after a cental Italian mountain area around the ancient town of L'Aquila was rocked by a major earthquake that struck in the early hours of Monday.

Many more dead were feared under rubble after thousands of homes were wrecked or left dangerously cracked. Hundreds of people were torn from their sleep and left homeless, wandering the streets.

The Italian government declared a state of emergency and set up a major operation sending in troops and emergency services to an area largely cut off after access roads were left blocked.

Local media reported the 27 deaths, but said many more bodies were expected to be unearthed after the quake - revised reports put its Richter scale strength at 6.2 - in central Italy's Abruzzo region.

The regional capital L'Aquila and the ancient town of Castelnuovo were especially badly hit. Four children were reported among the dead in one L'Aquila hospital.

Numerous buildings in the city collapsed, including a student dormitory in the historic centre, plus a four-storey building where up to 20 people were feared trapped.

The quake, preceded by two strong tremors and followed by an aftershock of 4.7 strength, occurred at 3.32 am from a depth of some five kilometres, according to civil defence authorities.

Tremors were clearly felt in Rome about 90 miles to the southwest, and as far afield as Naples. It was among the worst quakes to hit Italy in several decades, local reports said.

"The house just collapsed on top of me," said one survivor, Vittorio Perfetto, who was able to put his experiences onto the internet.

Another survivor, 23-year-old Guido Mariani, described how he spent a terrifying three hours buried under rubble until rescuers were able to reach him.

There were reports of hospitals in the region overflowing with injured and cars and other vehicles kept pouring in from immediate and outlying areas ferrying people with major and minor injuries.

Shocked survivors wandered streets huddled in blankets to ward off the early morning chill, with L'Aquila reduced to a ghostly quiet. The dome of a central church caved in while the city's cathedral was also damaged.

   The US Geological Survey reported the strength of the quake at 6.3, saying it was centred 95 kilometres north-east of Rome at a depth of 10 kilometres.

   A magnitude-4.7 aftershock was reported shortly after the quake, which was preceded by two tremors with magnitudes of 3.5 and 3.9, Italian authorities said.

   A section of the highway from L'Aquila to Rome was closed, and electrical and telephone service was cut off in many areas.

   Prime Minister Silvio Berlusconi cancelled a planned visit to Moscow as he declared the state of emergency. "Let's leave the politics to one side," he said. "We must help those who need help."