(SARAJEVO) - In a bid to rectify a legal error, hundreds of convicted Bosnian war criminals are set to be released and retried under a more lenient criminal code, outraging survivors who say they fear being traumatised all over again.

Twelve war criminals have already walked free since mid-October, six of whom were found guilty of genocide for their role in the massacre of some 8,000 Muslim men and boys at Srebrenica, the worst atrocity on European soil since World War II.

"It's scandalous!" said Hatidza Mehmedovic, who heads the Srebrenica Mothers association and whose husband and two sons were among those killed by Bosnian Serb forces in the eastern town at the end of Bosnia's 1992-95 war.

"Shame on those judges who reward genocide and who continue to punish the victims! We are disgusted and we are also scared since they already started to release the worst butchers," she told AFP.

The legal upset comes after the Strasbourg-based European Court of Human Rights (ECHR) in July ruled in favour of Goran Damjanovic -- a former Bosnian Serb soldier sentenced to 11 years for war crimes -- who argued he had been tried under the wrong criminal code.

Damjanovic said he should have been judged under the 1976 penal code that was in force when the crimes were committed, instead of being subjected to a stricter 2003 law that punishes war crimes with jail terms ranging from 10 to 45 years.

Under the previous criminal code, sentences ranged from five to 15 years, or capital punishment. Since Bosnia no longer applies the death penalty, 15 years would be the maximum punishment.

As a result of the ECHR ruling -- which also covered the appeal of another war crimes convict -- Bosnia's war crimes chamber is now obligated to hold retrials applying the less stringent previous criminal code, probably using a shortened legal procedure. Ten other verdicts have already been quashed.

The Sarajevo-based war crimes chamber of the Court of Bosnia-Herzegovina began operating in 2005 to assist the UN's International Criminal Tribunal for the former Yugoslavia in The Hague by dealing with lower-level cases on a national basis.

The local court has so far closed 110 cases, handing down several hundred guilty verdicts -- under what has now been deemed the wrong criminal code.

Bosnia's top constitutional court has given the war crimes tribunal three months to set a date for the retrials of those already released. Prosecutors and the accused may also use this time to reach a deal on fast-tracking new sentences.

'A bad message'

Citing a flight risk, state prosecutors have requested that those released be kept in detention while they await their new verdicts.

But for the dozen already freed, war crimes chamber judge Dragomir Vukoje said there were currently no restrictions on their freedom.

"Since there is no longer a valid verdict against them, there is no legal basis for their detention. They are free... there are no obstacles to them having (identification) documents," Vukoje told AFP.

Dozens of appeals for retrials are already pending, according to Dusko Tomic, a lawyer who specialises in war crimes cases.

With the scope of the fresh trials still unclear, Tomic predicted an uphill legal battle ahead if "we start all over again".

"It will be difficult now to call all those witnesses and victims again," he told AFP.

The Mothers of Srebrenica said victims had lost faith in the legal process and accused the court in a statement of sending out a "very bad message to future generations".

"The genocide verdicts were my only satisfaction," said Zejneba Cengic, whose husband and two brothers were murdered. "Is there anything human in those judges who decide to annul their verdicts?"