The world's top industrialized nations and leading oil consumers vowed Sunday to fight skyrocketing prices by boosting energy efficiency and accelerating investment in new technologies, while urging producers to expand production. Energy ministers from the Group of Eight countries, joined by China, India and South Korea, voiced "serious concerns" over record high oil prices, and said both producers and consumers would benefit from greater market stability. Ministers, meeting in the northern Japanese city of Aomori, focused on Sunday on how they could diversify their energy sources to both control rising demand for oil and rein in emissions of greenhouse gases blamed for global warming. "We simply must increase the level and breadth of investment all around the world," said US Energy Secretary Samuel Bodman. "That means promoting aggressive investment in renewable energy and other alternative energies technologies, as well as the development of tradition hydrocarbon resources." The 11 nations, which account for 65 percent of the world's energy consumption, grappled with oil prices that have hit record highs. Prices made a massive 8 percent gain Friday to US$138.54 on the New York Mercantile Exchange.