World powers Thursday urged Iran to begin a "constructive and serious dialogue" to answer international concerns over its suspect nuclear program as talks in Istanbul loom at the weekend.

"Iran's persistent failure to comply with its obligations... and to meet the requirements of the IAEA Board of Governors resolutions is a cause of urgent concern," foreign ministers from Group of Eight nations said in a statement.

"The ministers emphasized their desire for a peaceful and negotiated resolution to the nuclear issue," it added.

"They urged Iran to enter into a sustained process of constructive and serious dialogue without precondition on the basis of reciprocity and a step-by-step approach to restore international confidence in the exclusively peaceful nature of Iran's nuclear program."

Earlier US Secretary of State Hillary Clinton urged Iran to "credibly" answer international concerns over its suspect nuclear program at the Istanbul talks at the weekend.

"We continued to underscore that we hoped these talks result in an environment that is conducive to a sustained process that delivers results," Clinton told reporters after a meeting of Group of Eight foreign ministers.

"This is a chance for Iran to credibly address the concerns of the international community," she added.

"Iran, in coming to the table, needs to demonstrate that they are serious," the chief US diplomat said.

Iran is to meet Saturday in Istanbul with the United States, Russia, China, Britain, France and Germany to discuss its nuclear program, the first such talks since a similar meeting broke up inconclusively more than a year ago.

Most of those countries are represented in the Group of Eight which is composed of the United States, Canada, Russia, Britain, France, Germany, Italy and Japan.

The West suspects Iran's uranium enrichment program masks a drive to produce a nuclear weapon. Iran denies the charge, insisting its program is purely peaceful.