The United States and other members of the Group of Eight industrial nations say they are ready to respond to oil supply disruptions as Iran faces sanctions aimed at crippling its oil exports.

The G-8 leaders say increasing disruptions in the world oil supply "pose a substantial risk" to the global economy. But they stand ready to call upon the International Energy Agency to ensure that the oil market "is fully and timely supplied."

World leaders have warned Iran that misusing its nuclear energy program to develop a nuclear weapon is unacceptable.

Iran says it is enriching uranium only to create nuclear fuel. But its refusal to stop enrichment has led to sanctions aimed at crippling its oil exports _ penalties expected to take full effect in a few weeks.