UN leader Ban Ki-moon said Friday that the Syria conflict has become a "proxy war" and that the international powers must overcome rivalries to end the violence.
Evoking the UN's failure in the Srebenica massacre in Bosnia, Ban warned the divided UN Security Council that "the immediate interests of the Syrian people must be paramount over any larger rivalries of influence."
Ban gave his grim warning ahead of a UN General Assembly vote on a resolution deploring the Security Council's failure to act on the Syrian civil war and condemning the government's use of heavy weapons.
The UN secretary general said growing radicalization and extremism had been predicted at the start of the conflict in March 2011.
"The next step was also forewarned: a proxy war, with regional and international players arming one side or the other. All of these dire predictions have come to pass," Ban told the 193 member General Assembly.
Ban turned his fire on the Security Council which he said had become "paralyzed" by divisions over Syria.
Russia and China have vetoed three resolutions on Syria. They in turn accuse western nations of seeking to force the downfall of President Bashar al-Assad.
"Now, with the situation having worsened, they must again find common ground," he said.
Ban said the Syria conflict "is a test of everything this organization stands for" and recalled a recent visit to Srebenica, site of a massacre he called "one of the darkest chapters in this organization's history."
UN peacekeepers were accused of not doing enough to stop the slaughter of 8,000 Muslim boys and men in the Bosnian town in July 1995.
"I do not want today's United Nations to fail that test. I want us all to show the people of Syria and the world that we have learned the lessons of Srebrenica," the UN leader said.