The G-20, which comprises 19 of the world's biggest economies plus the European Union, is meeting in St Petersburg, Russia, just days before a U.S.Senate debate over military action in Syria.
News about the alleged use of chemical weapons by the country's government, led by Bashir al-Assad, has heightened tensions at the meeting.
(Read more: Pressure on Obama at G-20)
Jim Yong Kim, president of the World Bank who was present at discussions yesterday, told CNBC on Friday: "It's pretty much clear that chemical weapons were used and there was universal outrage."
"There were differences, of course, in what to do but we talked a lot about what we need to do now in terms of humanitarian outcomes of what's going on in Syria. It's really very disturbing what's already happening," he added.
The main division within the G-20 is between the U.S. and Russia, which is supportive of the Syrian regime. Russian President Vladimir Putin warned that the country would view strikes ordered without United Nations Security Council backing as an act of "aggression" – and hinted that Russia might take action itself in the event of a U.S. strike.
"Mr Putin has been asking a question that no-one has an answer for: if you overthrow Assad, who replaces him? This echoes what happened in Libya and Iraq," Bernard Sucher, board member at Aton, the Russian bank, told CNBC.
"They (the Russians) are stubbornly fighting back and log-jamming the Security Council."
(Read more: What's at stake for Russia in Syria)
U.S. President Barack Obama described the use of chemical weapons in Syria as a "red line" for the global community, but was criticized for his use of the phrase. Others have argued that the much-publicized debate over whether or not to take military action has removed the element of surprise, and warned that it has heightened tensions elsewhere in the region.
"The red line in the Middle East for the U.S. is not Syria. The red line for the U.S. is Iranian break-out nuclear capability," Ian Bremmer, the president and founder of Eurasia Group, told CNBC.
"For the Iranians it's very clear that for the U.S. to act, they're going to have to have a resolution which means they're going to have to say in advance that they're planning on acting and what they're planning on doing."