The political turmoil in Syria will dominate talks and overshadow any plans to tackle the global economy and tax avoidance at the G8 summit this week, while US President Barack Obama will seek help to get Syria to the negotiating table from the country's most powerful ally, Russia.

UK Prime Minister David Cameron is to lead a meeting of the Group of Eight (G8) - comprising Britain, the US, Japan, Canada, Russia, Germany, France and Italy - in Northern Ireland over the next two days.

But his plans to discuss and tackle economic issues, such as tax avoidance loopholes, will be overshadowed as the G8 attempt to end Syria's two-year civil war.

Obama is tipped to bolster support for bringing Syrian president Bashar al-Assad into negotiations, by trying to convince Russia's President Vladimir Putin to find common ground.

Obama will try and thrash out a fledging agreement at their first private face-to-face meeting in a year.

The Kremlin was initially angered by the G8 summit when it authorised US military support for the Syrian president's opponents.

On Sunday Putin slammed the summit and all 'enemies' of the Assad's regime for being cannibals, during a joint press conference with UK Prime Minister David Cameron.

"I think you will not deny that one does not really need to support the people who not only kill their enemies, but open up their bodies, eat their intestines, in front of the public and cameras," Putin said.

Cameron initially was set to make tax avoidance one of the key parts to the G8 summit and present plans to tackle the issue, which campaigners say costs $3tn a year.

"It is important we are getting our house in order," said Cameron.

However, according to the draft communiqué, G8 leaders will probably shy away from adopting a measure aimed at curbing tax avoidance.

Britain's campaigners say that Cameron's call for action will mean very little if the remaining G8 leaders do not follow suit.