The United States and its European allies plan to demand the immediate closing by Iran and ultimate dismantling of a recently completed underground nuclear facility near the city of Qum, The New York Times reported.
Citing unnamed US and European diplomats, the newspaper said the allies will also call at upcoming negotiations for a halt in the production of uranium fuel that is considered just a few steps from bomb grade, and the shipment of existing stockpiles of that fuel out of the country.
Iran last held talks with the six powers -- Britain, China, France, Germany, Russia and the United States -- in January 2011 with no results.
US Secretary of State Hillary Clinton had said the new talks would open April 13 in Istanbul. But Iran later said that Turkey was not an acceptable host after the NATO member cut oil imports from Tehran in response to US pressure.
The new demands will be the opening move in what President Barack Obama has called Iran's "last chance" to resolve its nuclear confrontation with the United Nations and the West diplomatically, the report said.
The UN Security Council has imposed four sets of sanctions on Iran because of suspicions over its nuclear program, which the West and Israel believe includes a drive to develop atomic weapons capability.
Some experts fear the tough conditions being set could instead swing the debate in favor of Iran's hard-liners, according to The Times.
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"We have no idea how the Iranians will react," the paper quoted one senior administration official as saying. "We probably won't know after the first meeting."
In a related story The Washington Post reported late Saturday. that a stealth surveillance drone operated by the CIA penetrated deep inside Iran over three years ago, snapped images of Iran's secret nuclear facility at Qum and returned home.
CIA stealth drones scoured dozens of sites throughout Iran, making hundreds of passes over suspicious facilities, before a version of the RQ-170 drone crashed inside Iran's borders in December, the report said.
The surveillance has been part of an intelligence surge that is aimed at Iran's nuclear program and that has been gaining momentum since the final years of George W. Bush's administration, The Post noted.
The effort has included eavesdropping by the National Security Agency, the formation of an Iran task force among satellite-imagery analysts, as well as an expanded network of spies, the paper added.
The expanded intelligence collection has reinforced the view within the White House that it will have early warning of any move by Iran to assemble a nuclear bomb, the report said.
According to the paper, the expanded intelligence effort has coincided with a covert campaign by the CIA and other agencies to sabotage Iran's nuclear program.
The administration of President Barack Obama has cited new intelligence reports in arguing against a preemptive military strike by Israel against Iranian nuclear facilities.