Iran's foreign minister warned today that a "lot of effort" was still needed as he joined negotiators from six world powers in Vienna to begin drafting a potentially historic nuclear deal.
"Preparing the draft agreement is a task that requires a lot of effort," Mohammad Javad Zarif said after touching down in the Austrian capital where talks resume in earnest tomorrow.
"If there are differences of opinion, which definitely exist, we will spend time to resolve them," he said, according to Iranian media.
The five permanent members of the UN Security Council plus Germany want Iran to reduce the scope of its nuclear programme to make any attempt to make a nuclear weapon undetectable practically impossible.
In return the Islamic republic, which denies wanting the bomb and says its aims are purely peaceful, wants all UN and Western sanctions lifted.
If the negotiators can manage to get a deal, this could finally resolve a standoff that has been simmering and threatening to escalate into conflict for the past decade.
"If the odds of the talks collapsing are high, the stakes of failure are higher," Ali Vaez, Iran analyst at the International Crisis Group, told AFP. "Time is of the essence."
Three previous rounds this year served to "review all of the issues and to understand each other's positions," White House spokesman Jay Carney said yesterday.
"And the next step is to begin to see if a text can be drafted. And that is something that presents obviously challenges," Carney told reporters.
"We hope the leadership in Tehran has given the entire delegation ... Instructions making it possible to move forward," Moscow's negotiator Sergei Ryabkov told the Voice of Russia.
The parties aim to build on an interim deal struck in Geneva in November under which Iran froze certain activities for six months in return for minor sanctions relief. The six months end on July 20.
