Iran and the five permanent members of the U.N. Security Council plus Germany, the so-called P5-plus-1, have been working on an agreement to end Iran's suspected nuclear weapons program in exchange for a lifting of economic sanctions. The talks were to resume Thursday.
French Foreign Minister Laurent Fabius, who played a central role in toughening terms of an interim deal reached Nov. 24 in Geneva, told the Wall Street Journal he was skeptical the United States, Britain, France, Russia, China and Germany would succeed in getting Tehran to unwind its nuclear capabilities to the point the country could no longer make a weapon.
Zarif's comments came Wednesday.
"The structure of our nuclear program has been maintained and the 20 percent enrichment can be resumed in less than 24 hours," Zarif said.
The semi-official Iranian news agency Fars said Zarif called the negotiation atmosphere "antagonistic."
"We will not stop any of our nuclear activities, but we will only voluntarily limit the level of our enrichment for a six-month period until comprehensive negotiations are held and a relevant decision is made for enrichment above the 5 percent grade," said Ali Akhbar Salehi, head of Iran's Atomic Energy Organization.
Salehi said Iran will continue its nuclear activities at the Natanz and Fordow enrichment facilities and in the Arak heavy water reactor and will also continue to conduct research and develop projects according to the deal. Salehi said none of the country's nuclear activities would be brought to a standstill, Fars said.
Fabius said his main concern is Iran's attitude about curbing its activities.
"It is unclear if the Iranians will accept to definitively abandon any capacity of getting a weapon or only agree to interrupt the nuclear program," he said.
Tehran has long defended what it calls its right to enrich uranium and to build nuclear reactors.
U.S. officials all the way up to President Obama have also expressed skepticism a final deal would be reached.
"I wouldn't say [the chances of success are] more than 50-50," Obama told a Washington audience at the Brookings Institution's Saban Center for Middle East Policy Dec. 7.
But he also said Washington was eager to find a way of reaching a final deal with Iran.
"Presuming that it's going to be a bad deal and, as a consequence, not even trying for a deal I think would be a mistake," Obama told the Saban Forum.
The Nov. 24 interim deal calls for Tehran to freeze parts of its nuclear program for six months in exchange for an easing of some Western economic sanctions. During this interim period, both sides agreed to try to reach a permanent deal to end Iran's nuclear threat.
Fabius told the Journal France and other EU countries that agreed to ease sanctions would keep the sanctions in place until the U.N. nuclear watchdog International Atomic Energy Agency verifies Tehran has frozen the required parts of its nuclear program to comply with the interim deal.
France, the United States, Israel and other allies maintain Iran is covertly trying to develop a capacity to build nuclear weapons, a charge Tehran denies, insisting its nuclear ambitions are limited to the peaceful generation of electricity and other civilian uses.
The technical, expert-level talks in Geneva, Switzerland, aimed at resolving differences over how to implement the interim accord, are to resume a week after Iran broke off an earlier round of talks in Vienna to protest additions to a U.S. sanctions blacklist.
Washington added 19 Iranian companies and individuals under existing sanctions. Tehran said the move violated the interim deal's spirit.