Strong aftershocks have rattled central Italy as hopes of finding any more earthquake survivors began to fade and the death toll rose to 267.

Some of hard-hit Amatrice's damaged buildings suffered more cracks after the biggest aftershock of the morning struck at 6.28am. The US Geological Service said it had a magnitude of 4.7, while the Italian geophysics institute measured it at 4.8.

The major aftershock was preceded by more than 50 overnight and was followed by another nine in the subsequent hour - some of the nearly 1,000 aftershocks that have rocked the seismic area of Italy's central Apennine Mountains in the two days since the original quake early on Wednesday.

Rescue efforts continued through the night and into Friday, but more than a day and a half had passed since the last person was known to be extracted alive from the rubble.

Read more: 37 killed by strong earthquake in central Italy as rescuers dig for survivors

While Prime Minister Matteo Renzi hailed the fact that 215 people had been rescued since the earthquake, civil protection officials reported only a steadily rising death toll that stood at 267 early on Friday.

Nevertheless, civil protection operations chief Immacolata Postiglione insisted that the rescue effort continued in full and had not switched to a recovery mission.

Rescue workers have noted that a person was pulled out alive from L'Aquila's 2009 quake after 72 hours, or three full days.

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"I confirm, once again as we have from the start, that the units that are doing the searches and rescues, including with dogs looking for other people trapped in the rubble, are absolutely fully active," Ms Postiglione said at the agency's early briefing on Friday.

On the ground, there was still determination to account for all missing, even though the number of people still unaccounted for is uncertain given the large number of visitors to the area for the final days of summer.

"Yes, there is still a chance to find someone alive," rescue dog handler Gianni Antonini said on Thursday.

Italian news reports said the first funerals were due to be held for some of the victims: in Rome, for the son of a local police chief who was in Amatrice with friends; and in Pomezia Terme for two grandmothers and their two grandchildren.

Read more: 37 killed by strong earthquake in central Italy as rescuers dig for survivors

The vast majority of the dead were found in Amatrice, the medieval hilltop town famous for its bacon and tomato pasta sauce, which was levelled by the quake.

The other victims hailed from the two other main hard-hit areas of Accumoli nearby and Arcquarta del Tronto and its hamlet Pescara del Tronto in the neighbouring Le Marche region.

Across the area, thousands were forced to abandon their homes, either because they were destroyed or were determined to be too unsafe. Overnight some 2,100 slept in tent camps, nearly 1,000 more than the first night in a sign that a significant number have found nowhere else to go.