The leaders of the G8 nations are to begin a summit in Northern Ireland, with Syria’s conflict set to dominate.
UK Prime Minister David Cameron met Russian leader Vladimir Putin – Syria’s key ally – on Sunday. They will each hold separate talks with President Barack Obama, who has indicated he will arm the rebels.
Mr Cameron, the host, is also keen to focus on global economic issues.
He hopes to oversee the launch of talks for an EU-US free trade deal and achieve progress on tax transparency.
The 39th Summit of the Group of Eight (G8) will be held in Lough Erne, County Fermanagh, on Monday and Tuesday.
Canada, France, Germany, Italy, Japan, Russia, the US and the UK will be represented.
Mr Cameron said he wanted “a meeting where we can look each other in the eye, cut through the obstacles and the opposition and generate the political will to solve the problems we face”.
The prime minister is scheduled to meet Mr Obama ahead of the opening of the summit.
But it comes amid allegations, made in The Guardian newspaper on Monday, that Britain spied on delegates who attended two G20 meetings in London in 2009.
The newspaper said documents, leaked by the ex-CIA whistleblower Edward Snowden, showed that British intelligence monitored the computers of foreign politicians and officials.
British spies are accused of setting up internet cafes to read delegates’ email traffic and penetrating the security on officials’ BlackBerrys to monitor email messages and phone calls. Targets are alleged to have included the Turkish finance minister and possibly 15 others in his party.
The newspaper says the documents suggest the operation was sanctioned in principle at a senior level in the government of the then Prime Minister Gordon Brown.
Observers say the revelations could cause tensions among delegates attending the G8, but Prime Minister Cameron refused to comment on them saying he “never comments on security and intelligence issues”.