World leaders head to the G20 summit in Russia

The World leaders of the G20 group of nations are set to meet in Russia for a financial summit, amid sharp differences over military action against Syria's government. Although the Syrian crisis in not officially on the G20 agenda, as the summit in St Petersburg is supposed to focus on the global economy,  ministers are expected to discuss Syria on the sidelines. Ahead of the talks, the host of the summit Russian President Vladimir Putin warned that action without United Nations approval would be "aggression". But President Barack Obama of the United States said the credibility of the international community was on the line. The Government of President Bashar Al Assad in Syria is accused of using chemical weapons against civilians on several occasions during the two-year long conflict; most recently on 21 August, in which the US has put the death toll at 1,429. President Assad's government has denied responsibility for the attack, and blamed rebel opposition, and Russia has said it was "ludicrous" that the Syrian regime would use chemical weapons. But Mr Putin did add that if there was clear proof of what weapons were used and who used them that Russia would "be ready to act in the most decisive and serious way".