In a judgment that is likely to have far-reaching implications for war crimes trials in Rwanda, Kosovo and East Timor, the tribunal elevated systematic rape from being a mere violation of the customs of war to one of the most heinous war crimes of all - a crime against humanity.

"This verdict is a significant step for women's human rights. Sexual enslavement in armed conflict is now legally acknowledged as a crime against humanity and perpetrators can and must be held to account," said Amnesty International in a statement after the decision.

The court ruled that the three veterans of the 1992-95 Bosnian war - who stood in silence as the verdict was read out - were guilty of the systematic and savage rape, torture and enslavement of Muslim women in 1992 in the town of Foca in south-eastern Bosnia. They were convicted on 19 separate counts.

"This is the first case where sexual slavery has been charged," the UN prosecutor Dirk Ryneveld said yesterday. "What sets this apart is that this is a case in which we have a large rape camp organisation. This is the first case of sexual enslavement and the only one with sexual assaults and no murders."

In the past international courts such as the tribunals set up in Nuremberg and Tokyo after the second world war have been reluctant to class wartime rape as a serious crime of war but the Hague tribunal took a much tougher line on the issue.

The judgment will give hope to thousands of surviving "comfort women" used as sex slaves by Japanese soldiers during the second world war who have been fighting in vain for recognition and compensation from the Japanese government.

The presiding judge, Florence Mumba of Zambia, described in graphic detail how the three Bosnian Serbs had in the summer of 1992 abducted girls as young as 12 and subjected them to appalling sexual torture in sports halls and a variety of "rape houses".

"The three accused are not ordinary soldiers whose morals were merely loosened by the hardships of war. They thrived in the dark atmosphere of the dehumanisation of those believed to be enemies," she told the court.

"Rape was used by members of the Bosnian Serb armed forces as an instrument of terror," the judge concluded at the end of the 11-month trial as she read out the verdict to the three accused.

"You abused and ravaged Muslim women because of their ethnicity and from among their number you picked whomsoever you fancied. You have shown the most glaring disrespect for the women's dignity and their fundamental human rights on a scale that far surpasses even what one might call the average seriousness of rapes during wartime."

Dragoljub Kunarac, 40, said to have been involved in a "nightmarish scheme of sexual exploitation", was given 28 years for rape and torture. Radomir Kovac, 39, was sentenced to 20 years for similar crimes. The third defendant, Zoran Vukovic, 45, was given a sentence of 12 years because prosecutors were able to produce less evidence in his case. He was, nevertheless, convicted of raping and torturing a 15-year-old Muslim girl who was about the same age as his own daughter.

The three had looked confident before the judgment was read out, shaking hands with their lawyers, but when the verdict was pronounced Kunarac sank slowly into his seat and shook his head.

In Sarajevo a group of Bosnian Muslim women reacted with fury to the sentences, which they regarded as insufficiently tough.

"We are shocked with the verdict. Justice has not been done, as the three received a minimum punishment for what they have done," argued Nezira Zolota of the Sarajevo association of former camp inmates.

Human rights groups estimate that tens of thousands of Muslim women and girls were systematically raped during the war. Many were deliberately impregnated so as to bear Serbian babies and advance the cause of ethnic cleansing.