Senior Italian officials yesterday backed an enquiry into whether illegal construction worsened the toll from this month's earthquake, despite criticism from Prime Minister Silvio Berlusconi.

Prosecutors are examining whether sub-standard building work was responsible for the collapse of many modern buildings in the central Abruzzo region, where the April 6 quake killed at least 294 people.

Mr Berlusconi, whose approval ratings have risen on his handling of the emergency, has played down the need for an enquiry, saying that reconstruction of thousands of damaged buildings must come first. Some 65,000 people are homeless.

"The inquiry into the earthquake is certainly not a waste of time," Alfredo Rossini, public prosecutor of the worst affected city, L'Aquila, told yesterday's La Repubblica newspaper.

"The event was very serious and all the people of Abruzzo, all Italians, want the truth, want answers, want justice."

Italian media have reported that corrosive sea sand was used in construction materials, and that some buildings contained far less than the legally required amount of cement, greatly worsening the impact of Italy's worst quake in three decades.

The speaker of the lower house, Gianfranco Fini, lent his support to the enquiry, telling a news conference that people had a "rightful wish to ascertain who is responsible."

President Giorgio Napolitano, one of Italy's most trusted politicians, said on Saturday that a disregard for building regulations had worsened the damage.

Mr Berlusconi, who has travelled to the devastated region several times, suggested on Saturday during a visit to a camp for victims that the investigation might merely "conclude that no one is responsible".

"If you like doing harm, my father told me you can do three things: be a criminal, a public prosecutor or a dentist."

Mr Berlusconi, Italy's second-richest man, started his own fortune in the construction sector.

His comments outraged judicial organisations and opposition politicians.