An Italian court on Monday found 15 police officers guilty of beating protesters at the G8 summit in Genoa in 2001 and sentenced them to between five months' and five years' imprisonment.

The heaviest sentence of five years was given to an inspector in the penitentiary police department. Thirty defendants were acquitted.

All those convicted are expected to appeal and none will go to prison until the appeals process is complete, which normally takes years.

Police were accused of organised brutality at the Diaz High school where protesters were camping during the summit, and later at the Bolzaneto police barracks where arrested protesters were taken.

Prosecutor Patrizia Petruzziello said the 40 protesters arrested suffered "four out of five" of the European Court of Human Right's classifications for "inhuman and degrading treatment".

A focus of protests by anti-globalisation, left-wing and anti-American demonstrators, the 2001 summit in the northern Italian city was one of the most violent in the history of meetings of industrialised nations.

The three-day gathering was marred by widespread rioting, in which one protester was killed and hundreds were injured during street battles with police.

Seventy-three protesters, among them Italian, British, Polish and Irish, were injured at the school.

In June last year a senior police officer belatedly admitted in court that police had "butchered" protesters.

In a graphic description of the violence, the former deputy police chief of Genoa, Michelangelo Fournier, said he had kept quiet until then "out of shame and a spirit of comradeship".