LONDON - World leaders gathering at the G8 Summit in Northern Ireland have been discussing how to end the Syrian conflict - and Russian President Vladimir Putin has been defending his support for Syrian leader Bashar al Assad, despite criticism from the his G8 counterparts.

Intense gun battles rage in the heart of Damascus and Aleppo on the same day that G8 leaders gather in Northern Ireland.

The gulf of disagreement on how to end the fighting appears to be widening.

Chris Phillips of Queen Mary University, London, argues Moscow has been the most consistent international player in the conflict.

"The Russians have always backed the principle of state sovereignty. As they see it, the Syrians have a right to conclude their affairs inside Syria as they wish. Russia itself is an autocratic regime and is not very keen on any major attempts to undermine the principle of state sovereignty and they are going to stand by that," said Phillips.

British Prime Minister David Cameron hosted Vladimir Putin on the eve of the summit, and reiterated his position that the Syrian president must go.

Putin was equally blunt, rejecting the position of Britain, the United States and France that the Syrian rebels should be armed.

"I want to draw your attention to the fact that Russia supplies arms to the legitimate government of Syria in full compliance of international law. We are not breaching any laws, let me emphasize that: nothing. We call on all our partners to act in the same fashion," said Putin.

Chris Phillips says that Western hesitation over supporting the opposition in Syria has emboldened Moscow.

"They're not actually willing to put in the kind of resources that the sides that want to preserve Assad are willing to put in. The amount of money and weapons being sent by Russia and by Assad's key ally Iran and their key supporters in Hezbollah from Lebanon is vast," he said.

President Putin will find that on Syria, it is him against seven others at the G8, says Professor Christopher Brown of the London School of Economics and Political Science.

"It would be actually an achievement if the G8 leaders could collectively put pressure on the opposition and on the government, to attend - to just getting a conference would be a position which is better than the position we're in at the moment," said Brown.

Brown says any progress hinges on the historic rival Cold War powers finding common ground.

"I think there'll be plenty of opportunities for Putin and Obama to sit down together without other people around. Funnily enough I think this is the right forum for dealing with Syria. It's not the right forum for dealing with economic problems, because it doesn't have China and India there," he said.

Healing the world economy is high on the agenda in Enniskillen. But analysts say the continuing bloodshed in Syria is exposing a widening divide among old rivals.