UNITED NATIONS - Russian President Vladimir Putin and his US counterpart Barack Obama sparred over the crisis in Syria in duelling UN speeches on Monday, each accusing the other of fuelling the carnage.

The Russian urged UN General Assembly members to unite to fight the Islamic State group and said it would be a disastrous error not to support Syria’s sitting president, Bashar al-Assad.

“We must address the problems that we are all facing and create a broad anti-terror coalition,” Putin said in his address, his first to the world body in a decade.

It is, he argued, an “enormous mistake to not cooperate with the Syrian group which is fighting the terrorists face-to-face.”

Obama said Washington was ready to work with Russia and even Iran against the Islamic State militants, but took a swipe at them for supporting Assad, whom he dubbed a child-killing tyrant.

Not to be outdone, the Russian leader blamed the rise of violent extremism on the United States’ military interventions in Iraq and Libya, which he said unleashed chaos in the Middle East.

Obama took the podium at the UN General Assembly ahead of Putin and hours before the pair were to hold their first meeting in over two years, at roughly 5:00 pm (2100 GMT).

The US president extended a cautious hand to his traditional foes, suggesting they work together to end the bloodshed in Syria. “The United States is prepared to work with any nation, including Russia and Iran, to resolve the conflict,” he said.

But the American leader made clear his opposition to Moscow and Tehran’s current policy of arming and supporting Assad. Rather than a bulwark against militant extremism, Obama argued, Assad drives Syrians into the arms of such groups by such acts as dropping “barrel bombs to massacre innocent children.”

Putin rejected this view, arguing that the IS group sprang out of the chaos left behind after US-backed forces ousted Saddam Hussein from Iraq and Moamer Gaddafi of Libya.

After the end of the Cold War, Putin argued, the West emerged as a new “centre of domination” of the world and arrogantly took it upon itself to resolve conflicts through force. This power led to the “emergence of areas of anarchy in the Middle East, with extremists and terrorists. “Tens of thousands of militants are fighting under the banners of the so-called Islamic State, and their ranks include former Iraqi servicemen,” he said. Putin said the current US policy of training and arming local rebel groups to fight militants was only adding fuel to the fire.

“The ranks of the radicals have been joined by the moderate Syrian opposition,” he said. “First, they are armed and trained, and then they defect to the so-called Islamic State.” Washington insists Assad must leave power before any settlement to the conflict, while European powers seem to be softening their stance, signalling he could stay on in an interim role.

In his address, Obama did not specifically address Assad’s fate, a key bone of contention in efforts to re-launch a bid to end a war that has left more than 240,000 dead since 2011. But he declared that there could be no return to the pre-war status quo, when Assad held sway.

Moscow has put Washington on the back foot by dispatching troops and aircraft to the war-torn country and pushing reluctant world leaders to admit that Assad could cling to power.

On the ground, Russia has started putting the pieces together by agreeing with Iraq, Syria and Iran that their officers will work together in Baghdad to share intelligence on IS.

Iranian President Hassan Rouhani said on Monday Tehran was ready to help bring democracy to war-torn Syria and Yemen and blamed the spread of terrorism in the Middle East on the United States.

Obama praised the efforts of the United Nations to improve human development, increase international cooperation and resolve crises, while also reducing poverty, and advancing democracy and individual liberties on “every continent.” “Of course, there have been too many times when collectively we have fallen short of these ideals. Over seven decades terrible conflicts have claimed untold victims, but we have pressed forward - slowly, steadily - to make a system of international rules and norms that are better and stronger and more consistent,” Obama said.

“Yet we come together today knowing that the march of human progress never travels in a straight line, that our work is far from complete that dangerous currents risk pulling us back into a darker more disordered world,” Obama added.

“Strongmen” leaders in charge of fragile states that breed conflict have caused many to flee, and “brutal networks of terror have stepped into the vacuum,” Obama said.

Obama also spoke of political polarization by the right and “sometimes” the left that create divisions, such as by “calling for the building of walls to keep out immigrants” in the nature of “a politics of us versus them.”

“Most ominously we see the fears of ordinary people being exploited through appeals for sectarianism, or tribalism, or racism, or anti-Semitism,” Obama said.