The United States and Japan called Sunday for urgent action on red-hot oil and food prices that could derail the global economy on the eve of a summit of the world s richest nations.

As US President George W. Bush arrived at this mountain resort, authorities sealed off Japan's northern island of Hokkaido, with demonstrations relegated to its largest city, Sapporo.

Group of Eight leaders will hold three days of talks in the resort town of Toyako that will be dominated by the fragile world economy, global warming and problems ranging from Zimbabwe to North Korea and Iran's nuclear ambitions.

In pre-summit talks, Japanese Prime Minister Yasuo Fukuda said he and Bush had agreed that urgent efforts are needed to tackle surging oil and food prices.

The dual crises "are having a negative impact on the world economy," Fukuda told a joint press conference. "We agreed there's a need for swift efforts on these fronts."

The leaders of the world's two largest economies also touched on climate change, North Korea's nuclear programme and aid to Africa.

Security was formidable across picturesque Hokkaido, with around 21,000 police deployed to protect the leaders as they huddle in a luxury hilltop hotel.

The leaders of the G8 -Britain, Canada, France, Germany, Japan, Italy, Russia and the United States -- will be joined by those of some 15 other countries including China, India, Brazil, Australia and eight African states for expanded sessions on global warming and poverty alleviation.