Then there are situations like East Timor, where 1,500 civilians were killed, 250,000 displaced, and where rape and torture was widespread when Indonesian troops and proxy gangs and militias tried to prevent a move for independence in 1999. Tiny East Timor's government, not wanting to upset delicate economic and diplomatic relations with its giant neighbour, is resisting calls for an international tribunal.

Nonetheless, experts in international law believe that a system is evolving that will, over time, give justice to people who have suffered at the hands of their own governments or those from other countries. They warn, though, that finding the best approach is a matter of trial and error and could yet take decades.

Renowned lawyer and judge with the Special Court for Sierra Leone, Geoffrey Robertson, stressed last week that the world was at a 'very rudimentary stage in delivering on international criminal justice', having taken concerted steps only over the past 10 years.

'Many mistakes have been made, particularly with the inefficiency and expense in some new courts,' Mr Robertson said from his chambers in London. 'I do think, however, that justice will have its own momentum and in time we will look back on these problems as teething troubles, and future generations will be amazed that we let people like Pol Pot, Augusto Pinochet and Idi Amin live happily ever after their tyranny.'

Of the three former dictators, only Chile's Pinochet is still alive, and although his regime is accused of killing thousands of opponents between 1973 and 1990, he is before courts on less serious charges of corruption. Amin, blamed for the deaths of 300,000 Ugandans during his 1971-1979 rule, died in exile in Saudi Arabia in 2003.

Khmer Rouge leader Pol Pot died in 1998 without being charged with any crimes, despite his 1975-1979 regime being blamed for the genocide of as many as two million Cambodians. But a recent decision by the United Nations to help fund and support a three-year national tribunal to try the foremost leaders of the atrocities has finally given survivors hope that justice will be done.

There are some concerns that the Cambodian government's insistence that its courts provide the majority of legal expertise will prejudice the chances of fair trials. That the tribunal's budget will be just US$56 million means that only a handful of those behind the genocide can be tried and other lesser figures will remain free.

Yet the fact that 26 years after the killing spree ended a tribunal finally appears likely is a sure sign of a changed international attitude towards human rights violations.

Since its establishment by a UN resolution in May 1993, the International Criminal Tribunal for the former Yugoslavia has charged 162 people, so far sentencing 21 to jail terms and acquitting five others. Arrest warrants have been issued for 10 more.

A second international tribunal was set up in 1995 following the slaughter of up to two million people in Rwanda the previous year. With nine judges and four trial chambers, the International Criminal Tribunal for Rwanda is presently hearing 25 cases and has handed down 19 judgments involving 25 accused. Among them is the world's only former leader to be jailed for genocide - caretaker prime minister during the killing spree, Jean Kambanda, who is serving a life sentence in Mali.

The International Criminal Court finally became reality on July 17, 1998, when a UN conference in Rome adopted its statute with a vote of 120 countries in favour, seven - including the US - rejecting the idea and 21 abstaining. It began operations on July 1, 2002, and anyone committing crimes under the statute since that date is liable to prosecution.

Five months before the court's prosecutor began taking cases - investigations of atrocities in the Darfur region of Sudan, northern Uganda and the Democratic Republic of Congo are under way - the Special Court for Sierra Leone was set up by the UN and Sierra Leone's government.

It deals with atrocities committed since 1996 in the African nation, and 11 people from the three groups involved in the conflict have been charged with crimes including murder, rape, extermination, enslavement, conscription of children into an armed force and attacks on UN peacekeepers and humanitarian workers.

A lack of funding is hampering the court's work and it is because of the high cost involved in such undertakings that the tribunals in the former Yugoslavia and Rwanda have been ordered to begin winding down operations. The biggest, the Yugoslavia tribunal, has 16 judges working in three courts and has so far spent an estimated US$1 billion - its budget for this year and last year is US$272 million.

That cost is just for prosecuting the main perpetrators of the crimes and national courts are trying those accused of lesser charges. The manner in which the trial of former Yugoslavian president Slobodan Milosevic has been conducted - it is in its second year and is likely to go into a third - has been widely criticised.

The tribunal's worth in healing the wounds of war has been further questioned by the non-arrest of former Bosnian Serb leader Radovan Karadzic and his army commander, Ratko Mladic, who were both charged with war crimes in July 1995, and are thought to be in hiding under Serbia's protection.

Sierra Leone's tribunal faces a similar problem: It has charged Liberia's former president Charles Taylor with genocide, but he is living in luxury in Nigeria under a deal brokered for his removal from power.

Concern is also widespread among international law experts about how fair the trial of ousted Iraqi dictator Saddam Hussein and his officials will be when it begins in September. They are being tried by Iraqi judges in a national court and many believe that that, along with heavy American influence, will prejudice the outcomes.

Such concerns were behind the creation of the International Criminal Court, although Mr Robertson believed it was more appropriately a forum for prosecuting crimes against humanity in countries where accountability was non-existent or the legal system had broken down.

Spokesman for the prosecutor's office of the court, Christian Palme, said a learning process was under way where lessons from the tribunals and ad hoc courts were being incorporated into the International Criminal Court's workings. The main difference was that the court was permanent and therefore had a potentially wider remit.

But the president of the New York-based International Centre for Transitional Justice, Juan Mendez, said the co-existence of the court and other forms of international justice would continue for some years. Some cases would be better suited to the court and others to other international means of justice.

'I have great hopes for the International Criminal Court, but there's always going to be a need for domestic jurisdiction to live up to its obligations,' Mr Mendez said. 'In an ideal world, we wouldn't need international justice - rather, domestic systems that function and do not let serious crimes go unpunished. But the way the world is, international justice comes in as a substitute when nations are unwilling or unable to provide redress for victims of human rights abuses.'

The process presently in place had flaws and was far from perfect, the observers agreed. Nonetheless, they suggested a system was evolving that would bring justice to the victims of the worst crimes - in coming years or perhaps decades.