European officials gathered in Turkey for talks on Iran's nuclear program have suggested that a serious commitment from Tehran to negotiate may be enough to allow another round of discussions in May, The New York Times reported Friday.

Citing unnamed diplomats, the newspaper said that a positive first step would be for Tehran to agree to allow the inspectors to visit all nuclear sites, including those Iran refused to show them in February.

The report came as senior diplomats from the United States, Russia, China, Britain, France and Germany -- known as the P5+1 -- prepared to gather at the negotiating table with Iranian counterparts in Istanbul on Saturday.

Foreign ministers from the Group of Eight major industrialized nations called Thursday on Iran to begin a "constructive and serious dialogue" while highlighting Tehran's "persistent failure to comply with its obligations."

US Secretary of State Hillary Clinton also fired a warning shot, saying the Istanbul talks were "a chance for Iran to credibly address the concerns of the international community."

But a source close to Tehran's delegation saying that Western comments ahead of the talks did not "give us much hope."

The Times cited the diplomats as saying that allowing the inspectors back in would help restore confidence and could be enough by itself to open the way to further talks.

Iran has fueled Western suspicious by denying the International Atomic Energy Agency access to the Parchin military base near Tehran, where the agency says Iran may have tested explosives for warhead research, the paper noted.

If the talks ultimately fail, both the United States and Israel have refused to rule out military action in order to stop Iran's steady enrichment of uranium to 20 percent purity, just a few technical steps from bomb-grade, The Times pointed out.