MILAN (AFP) - Islamic militants in Europe and the US are overwhelmingly men in their late 20s with criminal records who act independently of Islamic State in Iraq and Syria (ISIS), a study of the atrocities in the West has found.

The report, presented late on Thursday (June 29), found that since ISIS proclaimed its "caliphate" in June 2014, three years ago, 51 attacks have been carried out in the West in eight countries.

"Radicalisation and jihadist attacks in the West" was drawn up by experts at America's George Washington University, Italy's Ispi (Institute for International Political Studies) and the ICCT counter-terrorism centre in The Hague.

France was hit the hardest, suffering 17 attacks, followed by the United States with 16 and Germany with seven.

The attacks - which left 395 dead and at least 1,549 wounded - were carried out by 65 assailants.

Forty-three lost their lives, 21 were arrested, and one is on the run.

The average age of the attackers was 27 years and three months. The youngest was 15 years old, the eldest 52.

Nearly all of them were men - only two were women.

Seventy-three per cent were citizens of the country where they carried out the attack.

Fourteen per cent were lawfully resident in the country or were legally visiting from nearby countries, 5 per cent were refugees or asylum seekers, while 6 per cent were in the country illegally or awaiting deportation.

Seventeen per cent were people who had converted to Islam.

Eighty-two per cent were already known to the authorities before their attacks: 57 per cent had a criminal record and 18 per cent had already spent time in prison.

Only 18 per cent were foreign fighters, and in just 8 per cent of the attacks the order came directly from ISIS leaders.

In 66 per cent of the cases, the attackers had some form of connection to the ISIS group but acted alone.

And in 26 per cent of them, they had no connection with ISIS or other militant groups but were inspired by their call to arms.