Relatives of victims of the Italian earthquake have gathered in Amatrice for an evening Mass remembering dozens of the 292 people killed.

Construction crews earlier worked through the rain in the earthquake zone to build a tent complex to host the state funeral, as prosecutors took preliminary measures to sequester buildings that crumbled despite being renovated with public anti-seismic funds.

Firefighters placed the coffins in rows, with two little white caskets sandwiched between larger ones - evidence of the many children enjoying the final days of summer who were killed.

Relatives placed bouquets on the coffins and sat next to them quietly.

The Mass is the second state funeral for victims of the August 24 disaster that flattened three towns in central Italy. The first, held on Saturday, honoured victims from the Le Marche region. The latest funeral is for victims in neighbouring Lazio, which includes Amatrice.

The service, on the outskirts of Amatrice's obliterated medieval centre in the grounds of a Catholic home for the elderly, comes as Italy observes a second day of national mourning.

Crews using bulldozers and steamrollers worked through the night to erect a huge, open-sided tented roof to shelter the altar and the seating area. Civil protection officials said only 37 coffins would be on hand, since many families had opted for private funerals elsewhere.

Initially, authorities planned to hold the funeral in an airport hangar in the provincial capital of Rieti, 40 miles away, citing safety and organisational concerns. The quake area has seen more than 2,500 aftershocks and faces logistical problems in bringing relatives and officials into a town with only one serviceable access road.

But grieving residents rebelled at plans to let them watch it on TV or be bussed to Rieti, where many bodies were being housed in a makeshift morgue at the airport. Prime minister Matteo Renzi reversed course on Monday evening.

Some 231 quake victims were found in Amatrice and 11 more in nearby Accumoli. The bodies of as many as 10 people, including Amatrice's baker, are believed still buried in the rubble. Fifty people were killed in Le Marche.

Romanian prime minister Dacian Ciolos was attending the state funeral, as 11 of the dead were Romanians. About 8,000 to 10,000 Romanians live in the quake zone, many working in agriculture or as carers.

Italian prosecutors, meanwhile, took the first steps to investigate if construction firms or any others bore any responsibility for buildings that collapsed in the quake.

The ANSA news agency said Rieti chief prosecutor Giuseppe Saieva ordered Amatrice's collapsed primary school to be sequestered and entrusted Italy's financial police with investigating how public funds destined for anti-seismic renovations across the region were used.

The school collapsed during the quake despite being renovated in 2012 using earthquake funds. In addition, the church tower in nearby Accumoli collapsed on a home, killing a family of four, despite also having been recently renovated with earthquake funds.

Mr Saieva is investigating what was stipulated in the contracts to restore the buildings and what exactly was done.