Negotiators from six world powers and Iran on Friday began composing the text of a comprehensive agreement on Tehran's nuclear program, but remained far apart on key issues as they closed out a fifth round of talks.
With one month to go to their deadline, Western and Iranian negotiators each accused the other of failing to offer realistic terms for their long-awaited deal.
FOR THE RECORD
An earlier version of this story incorrectly said negotiators closed out a sixth round of talks on Friday. It was the fifth round.
Nevertheless, diplomats said they did make limited progress at the weeklong session in the Austrian capital, Vienna, and insisted they are still focused on completing the deal by the July 20 deadline.
The agreement would limit Iran's nuclear program to prevent it from gaining a weapons capability. In exchange, the six world powers -- the United States, Britain, France, Russia, China and Germany -- would lift the tough international sanctions that have crippled Iran's economy.
Mohammad Javad Zarif, Iran's foreign minister, joked that the preliminary text has "more parentheses than words," referring to sections that remain in dispute.
Still, he said there had been progress, because "we have started putting everything on paper ... in rather black-and white form."
Although the countries can extend the negotiating deadline under an interim deal they signed in November, July 20 "would be the best date for reaching an agreement," he said.
Diplomats acknowledged that the two sides appear to be holding back on making their best offers until the deadline is closer, a traditional negotiating strategy.
Their next meeting is scheduled to begin July 2 and is expected to continue until the deadline.
Zarif, at a news conference with Iranian reporters, said he had been assured by President Obama and other senior U.S. officials that the administration is eager to make a deal. But he said their offer didn't suggest they were serious.
"There is a need for that stance to be further manifested," he said.
A senior Obama administration official made a similar statement about the Iranians, saying Tehran has an opportunity to reach a deal if it demonstrates that it is serious about keeping its nuclear program peaceful.
"What is still unclear is if Iran is really ready," said the official, who declined to be identified citing diplomatic sensitivity.
The official said there had been no discussion yet of extra time for the negotiations. That is a sensitive question because an extension of the deadline could require an adjustment to the terms of the interim deal reached in November.
Some U.S. lawmakers, fearful that the administration might strike too lenient a deal, could block such an extension, sinking the diplomatic effort.
The U.S. official suggested that if the two sides can resolve the toughest issues, they might need only a brief extension to finalize a deal.
"If we get close and need a few more days, I don't think anybody will mind," the official said.
The official also confirmed that the negotiators had discussed the ongoing offensive by Sunni Muslim extremists in Iraq, which threatens that country's Iranian- and U.S.-backed government. But the official said it was a casual conversation -- like the inevitable chatter about the World Cup soccer tournament -- rather than a substantive discussion.
The official said Obama and Secretary of State John F. Kerry were paying close attention to the nuclear talks and were giving instructions to the U.S. negotiating team.
In the course of the week, diplomats have offered both optimistic and dire forecasts about the direction of the talks. They said that the two sides have slightly adjusted their positions since making their opening demands, but that they remain far apart on key points such as how many uranium centrifuges Iran would be allowed to keep to under the deal.