Islamist militants tortured a group of Italians before killing them during an attack on a restaurant in the Bangladeshi capital of Dhaka last week, a legal source said yesterday.

The bodies of the nine Italians, most of whom worked in the clothing industry, were flown back to Rome on Tuesday. Autopsies showed that many of them had been slashed with knives and had suffered slow deaths. Some had been mutilated, the source said.

In all, 20 people died in the Dhaka assault, which started late on Friday night. The victims, mostly foreigners, included Japanese, Indians and Americans as well as the Italians.

Islamic State said it was responsible for one of the most brazen attacks in Bangladesh's history, posting pictures of the five men they said took part in the onslaught.

Officials said most of the militants had attended prestigious schools or universities in Dhaka and Malaysia.

It was reported two of the six militants who stormed the Holey Artisan Bakery studied at the Malaysian campus of Monash University - Rohan Ibne Babul, the son of a Bangladeshi politician, and Nibras Islam.

The duo, both 20, was among five of the militants killed when police stormed the upmarket restaurant on Saturday morning.

The restaurant in Dhaka where the attack took place is popular with foreigners, and investigators in Rome are looking into whether Italians were specifically targeted, a judicial source said.

- Reuters