Steps are being taken to speed up the forthcoming trial of former Bosnian Serb military commander Ratko Mladic on genocide and war crimes charges, prosecutor Serge Brammertz has said.
He said the charge sheet had been amended to shorten the trial's length.
Gen Mladic is in UN custody in The Hague and is due to make his initial court appearance on Friday.
He is accused of atrocities committed during the 1990s Bosnian war, including the massacre of Muslims at Srebrenica.
Several war crimes trials at UN courts in The Hague have taken many years.
Asked how long the whole process could take, Mr Brammertz told reporters: "It is very difficult to say how long it will last.
"The problem will not be the prosecution, we have our updated charge sheet ready, it will be a question of how long the defence needs to prepare their case."
Mr Brammertz hailed Gen Mladic's arrest last Thursday in the village of Lazarevo, north of Belgrade, after 16 years on the run.
"His arrest confirms that no-one can count on impunity for war crimes," he said. "He is charged with crimes that shocked the conscience of the international community."
He thanked the president of Serbia and the country's security services for the arrest of Gen Mladic. But he said the detention of another key war crimes suspect, former Croatian Serb leader Goran Hadzic, should go ahead "without further delay".
Gen Mladic was admitted to the UN detention unit in The Hague on Tuesday.
He was flown to the Dutch city after a Serbian court rejected an appeal against his extradition. His lawyer had argued he was too ill to be tried, but Serbian doctors said he was fit enough to be extradited.
Upon his arrival, a spokeswoman for the International Criminal Tribunal for the former Yugoslavia (ICTY) said tribunal staff handed Gen Mladic his indictment and explained the rules and procedures to him.
He was then placed in an isolation cell for the night - standard practice for new arrivals at the prison - before being examined by a doctor the following morning.
He was also given a list of defence lawyers who could help him through the initial proceedings of the war crimes court.
Court registrar John Hocking rejected comments by Gen Mladic's lawyer and son that the former commander was disorientend and mentally unfit for extradition.
He said Gen Mladic's transfer to the court's detention unit had been "a very co-operative, very smooth procedure".
Gen Mladic has said he does not recognise the authority of the UN tribunal.
When he appears in court at 0800 GMT on Friday, he will be asked to formally confirm his identity and enter a plea to each of the charges against him.
The former military commander could decline to plead at his first appearance, instead opting to delay a formal response by up to a month.
The prosecution has charged Mladic with genocide, persecution, extermination, murder, deportation, inhumane acts and cruel treatment for his alleged part in a plot to achieve the "elimination or permanent removal" of Muslims from large parts of Bosnia in pursuit of a "Greater Serbia".
He is accused of masterminding the 1995 Srebrenica massacre of about 7,500 Bosniak (Bosnian Muslim) men and boys, Europe's worst atrocity since World War II.
He is also charged over the 44-month siege of the capital Sarajevo from May 1992 in which 10,000 people died.
Gen Mladic's arrest is considered crucial to Serbia's bid to join the European Union.