Former US President Bill Clinton has paid tribute to victims of the 1995 Srebrenica massacre in Bosnia - Europe's worst atrocity since World War II.
Mr Clinton, who was US president when the Bosnian war finally ended in 1995, was unveiling a memorial cemetery for more than 7,000 Muslim men and boys who died in Srebrenica.
They were executed by Bosnian Serb forces who overran the town, despite its designation as a United Nations "safe haven".
"We must pay tribute to the innocent lives, many of them children, snuffed out in what must be called genocidal madness," Mr Clinton told thousands of victims' relatives at the memorial.
"Srebrenica shattered the illusion that the end of the Cold War would sweep away such madness."
At the ceremony on Saturday, a large crowd heard a choir dressed in white sing solemnly on a hillside.
The new memorial - which took a year to build and cost about $5m - lies just across the road from the old UN base where thousands of Bosnian Muslims sought sanctuary in vain.
"Let us who still live remember our obligation to them, to establish a lasting and just peace", Mr Clinton said.
Children should be taught to trust, not to hate, he added - "to choose the open hand over the clenched fist."
The massacre galvanised the West and Mr Clinton's administration to intervene militarily to stop the war.
The BBC's Nick Hawton says many locals have mixed feelings about Mr Clinton's presence. They are grateful that US intervention helped to end the war, but many ask why Washington did not take action sooner.
Mr Clinton said the massacre was "the beginning of the end of genocide in Europe" because it enabled him to secure Nato support for the bombing that pushed back the Bosnian Serbs and led to peace.
Srebrenica was the worst massacre to take place during three years of bloody ethnic conflict between Bosnian Muslims, Croats and Serbs as part of the break-up of Yugoslavia.
More than 250,000 people were killed during the war.
Fathers and sons
The Srebrenica memorial site is shaped like the petals of a flower.
Ten thousand white tombstones will eventually stand there.
Widows of those who died wanted Mr Clinton to be the person to open the new memorial site, with one telling the BBC: "He is the only man with the moral authority to do so".
Families at the ceremony were burying a further 107 victims alongside 882 already laid to rest at the cemetery.
The victims included three Delic brothers and their father - the youngest 17 and the oldest 75.
On Friday during a visit to Kosovo, Mr Clinton urged Kosovan Albanians to seek reconciliation with their Serbian neighbours.
"No outsider, including me, could force you to forgive anyone," he told a crowd at Pristina University.
"But you should try. Not for them, but for you. I want you to be free."
Despite an international outcry over the Srebrenica massacre, only two people have ever been convicted for involvement in it.
Our correspondent says many feel reconciliation can only occur when the two former Bosnian Serb leaders, Radovan Karadzic and Ratko Mladic, face justice.
Both men, who are charged with genocide at Srebrenica, have been on the run for the past eight years.