Italian prosecutors on Tuesday requested prison sentences of four years each for seven scientists accused of underestimating the risks of an earthquake in L'Aquila in 2009 that killed 309 people.

The scientists are all members of a special committee set up to evaluate the risks of natural disasters, which held an emergency meeting in L'Aquila on May 31, 2009 -- six days before the fatal earthquake which devastated the city.

The meeting was called following a series of small tremors and concluded that it was impossible to determine whether a bigger earthquake could follow, although it did call for strict adherence to anti-quake measures in the area.

Prosecutor Fabio Picuti said there had been "an incomplete, inept, unsuitable and criminally mistake analysis" made by the scientists.

He said the statement issued by the committee before the earthquake had contained "banal, useless, self-contradictory and mistaken information".

Some of Italy's leading scientists are among the seven defendants, including Enzo Boschi, a former director of the National Institute of Geophysics and Vulcanology, and Claudio Evo, a physics professor at Genoa University.

Picuti picked up on a phrase attributed to Boschi in which he reportedly said: "I would reject (the possibility) of an earthquake."

"People died because of this phrase," Picuti said.

Defence lawyers are expected to present their final arguments on October 9 and 10 and a verdict is due before October 23, Il Tempo daily reported.