World leaders were gathering on Friday for G8 talks on global security and development, amid calls to deliver on past promises and a brewing dispute on how to shore up fragile economic recovery.
"At the Muskoka summit, I will join my fellow G8 leaders to take action on some of the world's most pressing problems," Canadian Prime Minister Stephen Harper pledged, in a message to delegations.
"We will make a real difference and deliver results," he vowed, as thousands of delegations, journalists and activists descended on eastern Ontario province for two back-to-back summits.
Under a tight security blanket, leaders from the Group of Eight richest nations were on Friday meeting in an exclusive, remote hotel resort in Huntsville, Muskoka, some 220 kilometers (140 miles) north of Toronto.
Then on Saturday and Sunday they will join others from the Group of 20 developed and emerging nations for a summit in the city here, with 20,000 police deployed for a huge billion-dollar security operation.
The key themes of the G8 talks were "growth and confidence," European Union president Herman Van Rompuy told journalists, with the leaders first set to huddle behind closed doors for a working lunch to discuss the world economy.
"The global recovery is progressing better than previously envisioned, although at different speeds," Rompuy said. "Restoring confidence in budgetary policies goes hand in hand with growth strategies."
For the first time the leaders are publishing figures in a bid to "provide a candid assessment on what the G8 has done," they said in a report.
The so-called Muskoka Accountability Report lists country by country the pledges each nation has made since 2002 in key areas such as aid, economic development, health and food security and how far they have met them.
"In some areas, the G8 can point to considerable success; in others it has further to go to deliver fully on its promises," the report says.
US President Barack Obama said he was calling for "a new era of engagement that yields real results for our people -- an era when nations live up to their responsibilities and act on behalf of our shared security and prosperity."
British Prime Minister David Cameron, making his first appearance at a major national summit since taking power last month, also suggested such meetings rarely resulted in "tangible global action."
"Too often these international meetings fail to live up to the hype and to the promises made," he wrote in an editorial in Canada's daily Globe and Mail.
"So the challenge for the upcoming G8 and G20 is to be more than just grand talking shops."
But tensions over how to sustain fragile growth as nations emerge from economic crisis are set to overshadow the back-to-back talks.
Obama has urged his European allies not to curtail massive stimulus packages, amid fears severe austerity measures could trigger a double-dip recession.
But German Chancellor Angela Merkel has insisted deficits must be cut in the wake of the eurozone debt crisis that forced Berlin to provide the lion's share to a rescue mechanism in the face of stiff domestic opposition.
"I think that there will be very fruitful, but also very contentious, debates on this issue," Merkel acknowledged.
US Treasury Secretary Timothy Geithner sought to play down America's differences with Europe telling the BBC the two sides "have much more in common than we have differences."
"Everyone agrees that those deficits have to come down over time to a level that's sustainable," he said. But he warned the world "cannot depend as much on the US as it did in the past."
The leaders of six African nations will also join G8 heads for Friday's talks focused on helping the continent fight terrorism and achieving millennium goals to improve poverty.
"The EU-Africa relationship is a priority for us. We insist particularly on the EU commitment to peace and security in Africa," said Van Rompuy.
One of the main focuses will also be the health of mothers and babies, with Harper pledging the G8 summit would champion a new initiative in developing countries.
Colombian President Alvaro Uribe and his Haitian counterpart Rene Preval, were also to join the G8 talks later Friday along with Jamaican Prime Minister Bruce Golding to discuss security and global threats.