The leaders of Group of Eight ( G8) major industrial nations said on Saturday that they remain united in their "grave concern" over Iran's disputed nuclear program, while urging Tehran to address such concern without delay.

"We remain united in our grave concern over Iran's nuclear program. We call on Iran to comply with all of its obligations under relevant UNSC (United Nations Security Council) resolutions and requirements of the International Atomic Energy Agency's (IAEA) Board of Governors," the G8 leaders said in a declaration issued after their summit at the Camp David, the U.S. presidential retreat in the state of Maryland.

The G8 leaders urged Iran "to continuously comply with its obligations under the Nuclear Non-Proliferation Treaty, including its safeguards obligations," the declaration said.

They also demanded Iran "address without delay" all outstanding issues related to its nuclear program, such as questions concerning possible military dimensions, while expressing the desire for "a peaceful and negotiated solution to concerns over Iran's nuclear program."

The G8 summit was held days ahead of the next round of resumed talks on Iran's nuclear program due on May 23 in Baghdad, Iraq, which will be attended by five G8 nations, including Germany, France, Russia, the United Kingdom and the United States, as well as China.

The first round of talks, held in Istanbul, Turkey, in April, ended on a positive note which eased the rising tensions between Tehran and the U.S.-led West that threatened to lead to armed confrontation.

Iran has maintained that its nuclear program is purely for peaceful purposes, but the U.S.-led Western nations suspect that it is seeking to develop a nuclear weapon.

The G8 leaders welcomed the resumption of the talks, while urging Iran "to seize the opportunity" to resolve the dispute, by engaging in detailed discussions about near-term, concrete steps that can, through a step-by-step approach based on reciprocity, lead towards a comprehensive negotiated solution, the G8 declaration added.

U.S. President Barack Obama, who hosted the G8 summit at Camp David, told reporters that G8 leaders "are firmly committed to continuing with the approach of sanctions and pressure in combination with diplomatic discussions."

The U.S. has imposed tough economic sanctions on Tehran in an attempt to persuade it from acquiring a nuclear weapon, which Washington warns could lead to military strike by the U.S. and its allies, especially Israel.

"And our hope is that we can resolve this issue in a peaceful fashion that respects Iran's sovereignty and its rights in the international community, but also recognizes its responsibilities, " Obama said.

In another move to exert pressure on Iran, the G8 leaders said a statement that they "stand ready to call upon the international Energy Agency to take appropriate action to ensure that the market is fully and timely supplied" in case of further disruption of oil supplies.

This indicated that the G8 leaders support Obama's proposal to tap oil stocks for the second time in two years, if tensions flare up in the West's nuclear standoff with Iran, a major oil supplier.