Italian authorities have readied an evacuation plan for G8 leaders attending a summit in the earthquake-hit city of L'Aquila in the event of a tremor of a 4.0 magnitude or higher, a source close to organisers said.

The source said the civil protection agency had prepared plans to evacuate leaders to Rome by air if needed. Summit meetings and events would then continue in the Italian capital.

The mountain city of L'Aquila has suffered repeated aftershocks after an April quake killed nearly 300 people and left thousands homeless. Italy moved the summit from a Sardinian island to the town in a show of solidarity with the victims.

Dozens of leaders at the event including U.S. President Barack Obama will be housed in a spartan police school facility built to anti-seismic standards, but a 4.1 magnitude tremor last week sparked new fears a quake would disrupt the event.

"There's no risk," Prime Minister Silvio Berlusconi told the Il Giornale daily. "Even if there was a quake, all the guests would be absolutely safe."

Foreign Minister Franco Frattini told the Il Messaggero daily summit that the organisers had "foreseen all the possibilities".

"From the seismic point of view one can't predict anything but we are ready," he said.