The ministers' also used stronger language to describe the risks to economic growth in their communique on Saturday than the threat of inflation, which has drawn unusually hawkish comments from the Federal Reserve and the European Central Bank.
'Elevated commodity prices, especially of oil and food, pose a serious challenge to stable growth worldwide, have serious implications for the most vulnerable and may increase global inflationary pressure,' they said in a communique.
Treasury Secretary Henry Paulson warned that high oil prices could prolong the U.S. downturn and European Union Economic Commissioner Joaquin Almunia said the U.S. was at risk of 1970s style stagflation.
The run-up to talks in the Japanese city of Osaka had been dominated by a link between a dollar slide and a doubling of oil prices in the past 12 months.
Japanese Finance Minister Fukushiro Nukaga said eight nations did not discuss currencies or intervening in foreign exchange markets in the meeting. Paulson refused to rule out intervention last week when he and other U.S. officials expressed concern about the weak dollar.
G8 countries, mostly importers of crude, wield little influence over oil markets that are driven by demand from India and China and concerns about supplies. But they can try to arrest a slide in the U.S. currency that has prompted investors to buy oil futures and other commodities to hedge dollar risks.
Italy floated a plan to make it more expensive to bet on oil prices in the futures markets, Italian Economy Minister Giulio Tremonti told reporters before the meeting.
The communique made no specific reference to the plan.
'We ask relevant national authorities to examine the functioning of commodity markets and to take appropriate measures as needed,' the ministers said.
They asked the International Monetary Fund and the International Energy Agency to work with national authorities to analyze real and financial factors behind commodity price rises.
Britain and the United States have in the past been reluctant to back intervention in oil futures markets. Canada's Finance Minister Jim Flaherty said markets should be allowed to work on oil prices. Canada is a net exporter of oil.
The ministers said the combination of rising prices and the risk to growth made 'policy choices more complicated.'
Almunia said the most important challenge for policy makers was to avoid stagflation -- a combination of stagnant economies and high inflation.
'The risk is high in the United States,' Almunia told the Nikkei Japanese business daily.
Paulson said U.S. economic growth could pick up this year even with lingering impact of a housing market meltdown and credit crisis.
'While we are still working through housing and capital markets issues, and expect to be doing so for some time, we also expect to see a faster pace of U.S. economic growth before the end of the year, while recognizing that the recent increase in oil prices risks prolonging the U.S. economic downturn,' he said.
Oil prices have rallied in tandem with a slide that has seen the dollar nearly halved in value against the euro in six years.
The Dallas Federal Reserve said in a paper last month the U.S. currency's slide had contributed about one-third of a $60 increase in oil prices between 2003 and 2007.
Anger over oil prices near a record $140 per barrel has spilled on to streets around the world. Truckers' strikes turned violent in Spain, Malaysians marched against the government and authorities from Thailand to the Netherlands face protests over rising pump prices.
The G8 groups the United States, Japan, Britain, France, Italy, Germany, Canada and Russia.