Ottawa: Foreign ministers from the Group of Eight leading industrial nations will call on the international community to take "appropriate and strong steps" to show its resolve over Iran's nuclear activities.
A draft of the final communique also said the G8 remained open to dialogue with Tehran, which denies widespread western charges that it is seeking to make atomic weapons.
The G8 ministers will end a two-day meeting in Canada on Tuesday.
In meetings outside the Canadian capital on Tuesday, US Secretary of State Hillary Rodham Clinton and her fellow foreign ministers from G8 will warn Iran again that it faces fresh penalties if it doesn't come clean on its nuclear program.
However, with Iran refusing to comply, their message will largely be directed at a country not represented at the talks here: China, a permanent member of the UN Security Council that is not a G8 member.
Support from China, a vocal opponent of sanctions, is critical as it wields veto power on the council.
However, until recently, it had balked at the mere suggestion of taking additional punitive steps against Iran. That, Clinton suggested, is now changing.
In an interview with Canadian television on Monday, Clinton said China shared the view of the US, its European allies and Russia that "a nuclear-armed Iran is not acceptable."
"I think as the weeks go forward and we begin the hard work of trying to come up with a Security Council resolution, China will be involved, they will be making their suggestions," she said.
A senior US official told reporters traveling with Clinton that the Chinese "have said now that they will engage on the elements of a sanctions resolution."