"I tell all those who criticise the work of the Hague tribunal, and there are such critics in Croatia, that the tribunal has achieved extraordinary results," del Ponte said at the International conference called "Establishing the Truth About War Crimes and Conflicts" in Zagreb on Thursday.
She, however, admitted, that a lot of work still needed to be done in the search for the truth about the conflicts and war crimes.
Del Ponte said the UN tribunal had processed the gravest crimes and established indisputable facts about the events in Srebrenica, at Ovcara and other sites in the former Yugoslavia where grave crimes had been committed.
She went on to say that after the recent wars in former Yugoslavia it was difficult to achieve truth and justice, notably to the satisfaction of all parties.
Challenges are still serious, she said. The tribunal is your partner and we shall continue working with national courts, del Ponte said.
ICTY president Fausto Pokar said the tribunal was limited by establishing the part referring to the judicial truth which does not meet the need of the society to establish the full truth.
"After the ICTY wraps up its work, local courts must continue to work on establishing the truth and the international community must help," Pokar said.
He said that so far the UN war crimes tribunal in The Hague has indicted 161 people, of whom 53 have been processed while 61 are still awaiting trial, including the six fugitives.
The state prosecutors of Croatia, Serbia and Bosnia-Herzegovina spoke about the work of national judiciaries concerning the establishing of the truth about war conflicts.
Croatian Chief State prosecutor Mladen Bajic said that by 2001, war crimes charges had been pressed against 4,500 persons of whom 3,700 are under investigation, on trial or have already received verdicts.
He said that since 2001 authorities have taken a more serious approach to investigating crimes committed by members of the Croatian Army and the police, adding that this was important for the credibility of Croatia's judiciary.
Bajic said that fair and legal criminal proceedings could contribute to establishing the truth and help historians to give a final judgement.
His Serbian counterpart Vladimir Vukcevic said that court proceeding were important for informing the public in Serbia that had been exposed to Milosevic's propaganda for years about what had really happened at mass executions sites, such as Ovcara.
"People who still believe in 'our heros' must understand that these people are war criminals and profiteers," Vukcevic said.
Bosnian Chief Prosecutor Marinko Jurcevic said Bosnia's Prosecutor's Office was short in staff and equipment, stressing that 70 prosecutors were currently working on 1,000 war crimes cases.