Gladiators may have fought and died to entertain others in the brutality of the Roman arena but they appear to have abided by a strict code of conduct which avoided savage violence, forensic scientists say.

Tests on the remains of 67 gladiators found in tombs at Ephesus in Turkey, center of power for ancient Rome's eastern empire, show they stuck to well defined rules of combat and avoided gory free-for-alls.

Injuries to the front of each skull suggested that each opponent used just one type of weapon per bout of face-to-face contact, two Austrian researchers report in a paper to be published in Forensic Science International.

Savage violence and mutilation, typical of battlefields 2,000 years ago, were out of order.

And the losers appear to have died quickly.

Despite the fact that most gladiators wore helmets, 10 of the remains showed the fighters had died of squarish hammer-like blows to the side of the head, possibly the work of a backstage executioner who finished off wounded losers after the fight.

The report confirms the picture given of battles in the arena by Roman artwork, which suggests gladiators were well matched and followed rules enforced by two referees.