Iran's six-month temporary rollback of its nuclear activities agreed to in the recent deal has not begun and the start date has not yet been set, a spokesman for EU foreign policy chief Catherine Ashton told AFP on Wednesday.
"The actual date for the beginning of the six-month period of the first step has yet to be decided," the spokesman, Michael Mann, said.
"It will also depend on the outcome of technical discussions with Iran about the implementation arrangements that will take place soon," he added.
In a major breakthrough Sunday in Geneva, Iran agreed with the United States, China, Russia, Britain, France and Germany to freeze some its nuclear work in exchange for minor sanctions relief.
This six-month stop is meant to make it more difficult for Iran to develop a nuclear weapon and to build confidence while Tehran and the P5+1 hammer out a long-term accord.
One Western diplomat in Vienna, headquarters of the International Atomic Energy Agency (IAEA), said they expected the six months to begin in January and that the expert-level talks would "likely" take place next week.
"It is all understandably vague but my understanding is that the six months start in January," the diplomat told AFP on condition of anonymity.
"The experts are going to be talking next week about how you translate that document (Sunday's deal) into something which is more specific and practical.... The momentum behind this is really very strong. Everyone realizes we have a limited opportunity to get this right," said the diplomat.
The six powers, Iran and the IAEA are to create a Joint Commission to work out exact timing and how the IAEA will monitor Iran's compliance, reported AFP.
A second diplomat told the news agency that these technical and logistical details "need to be worked out in the coming days" but that a "specific timeframe for these meetings is still being determined."
A spokeswoman for the Iranian Foreign Ministry said Tuesday that a fact sheet on the deal on the While House website was inaccurate, and that the deal with western powers left Iran with more leeway on its nuclear program than the sheet had implied.
Israeli leaders have been critical of the deal, which they argue left Iran dangerously close to obtaining a nuclear weapon.
Meanwhile, Iran’s President Hassan Rouhani has been gloating over the agreement. On Tuesday, he wrote on Twitter that the Geneva deal was a “very positive first step” and said it “shook the foundations” of the international sanctions regime.
In a later television interview, he expressed satisfaction over his country’s deal with the west, which he said has left Israel diplomatically isolated.