By Paul Richter, Tribune Washington Bureau

VIENNA — Iran and six world powers Wednesday formally began a two-month diplomatic sprint to complete a deal aimed at preventing Tehran from developing the ability to build nuclear weapons.

Top diplomats from the world powers — the United States, Britain, China, France, Germany and Russia — met with the Iranians, and among themselves, in various combinations all day and into the evening.

Although both sides are eager to make a deal, they remain far apart in their views. Representatives of the six-nation group arrived in Vienna without a detailed script for how they would resolve the differences.

The group is moving “to a new phase in the negotiations in which we will begin pulling together” ingredients for a deal, said Michael Mann, a spokesman for European Union foreign policy chief Catherine Ashton.

In past sessions, negotiators have sought to lay out all the issues. For the next nine weeks, they hope to write the text of an accord that they call the “comprehensive joint plan of action.”

Abbas Araqchi, Iran’s deputy foreign minister, told Iranian journalists Tuesday evening that the diplomats had cleared their calendars from July 1 to July 20 to enable them to complete a deal.

The agreement is intended to give Iran relief from crushing international economic sanctions in return for its commitment to safeguards intended to prevent it from acquiring nuclear weapons capability. The two sides must resolve half a dozen major issues that divide them, and it is expected that the bargaining will become intense as the deadline approaches.

A senior U.S. official Tuesday cautioned against excessive optimism given the wide differences that remain.

Even so, various diplomats say the nations are edging toward compromises on some key issues, including the monitoring of Iran’s nuclear infrastructure, the fate of the disputed Arak heavy-water reactor and the underground Fordow uranium enrichment facility, and the expected duration of the deal.

Though the U.S. official sought to lower expectations, Araqchi told journalists that a deal is “within our reach,” provided negotiators can exert the necessary political will.

AFP Photo/Atta Kenare