Iran said it hopes enough progress will be made at talks with major powers this week to enable negotiators to start drafting by mid-May a final accord to settle a long-running dispute over its nuclear program.

The Islamic Republic and six world powers will hold a new round of talks in Vienna on Tuesday and Wednesday intended to reach a comprehensive agreement by July 20 on how to resolve a decade-old standoff that has stirred fears of a Middle East war.

"We will finish all discussions and issues this time to pave the ground for starting to draft the final draft in Ordibehesht (an Iranian month that begins in two weeks)," Foreign Minister Mohammad Javad Zarif said upon arrival in the Austrian capital.

A U.S. official gave a similar timetable last week, voicing hope that the drafting of an agreement could begin in May.

Iran says its enrichment program is a peaceful bid to generate electricity and has ruled out shutting any of its nuclear facilities.

But the United States and some other Western countries have accused Iran of working on developing a nuclear bomb capability and Israel has threatened to attack its long-time foe Iran if diplomatic efforts fail.

Iranian Deputy Foreign Minister Abbas Araqchi, a top negotiator, was quoted as saying by Press TV on Sunday: "We hope that in the upcoming talks, we would be able to bring the views closer and narrow the differences regarding major issues, so we could get to the details ... and start writing the text."

The relatively upbeat comments by Zarif and Araqchi appeared designed to underline Tehran's commitment to reach a comprehensive deal by the July deadline, though Western officials say wide differences remain between the two sides.

The six powers - the United States, France, Russia, China, Britain and Germany - want Iran to scale back its nuclear program to deny it any capability to quickly make a nuclear bomb, if it decided to pursue such arms.

TALKS STILL IN EARLY STAGES - RUSSIA

Iran says the powers must respect what it calls its right to a peaceful nuclear program, including the enrichment of uranium. Such activity can have both civilian and military uses.

"We believe that our partners should make important decisions which includes respecting the existing realities and respecting Iran's rights," Zarif said.

"We are ready to cooperate to remove any ambiguity about the peaceful nature of our nuclear program."

A senior U.S. administration official, speaking on Friday, said both sides had intended to spend March and April going over "every single issue that we believed had to be addressed in a comprehensive agreement" before work started on drafting in May.

"We are on pace with that work plan, looking toward beginning drafting in May," the official said.

Russia's chief negotiator said Moscow had no special expectations for this week's meeting. Deputy Foreign Minister Sergei Ryabkov said talks on a number of issues were still in early stages and the meeting should produce a basis for further talks, Itar-Tass news agency reported.

The aim of the negotiations that began in February is to hammer out a long-term deal to define the permissible scope of Iran's nuclear program in return for a lifting of sanctions that are damaging its oil-dependent economy.

In November, Iran and the six nations agreed an interim accord to curb Tehran's atomic activities in exchange for some easing of sanctions. The six-month deal, which took effect on January 20, was designed to buy time for talks on a long-term deal.

Iran has said it had useful expert-level nuclear talks with world powers in Vienna last week, addressing all major technical issues in the way of a final settlement.

Iranian negotiator Hamid Baeedinejad told the official IRNA news agency on Saturday that the results of those technical discussions would be submitted on Monday to Zarif and European Union foreign policy chief Catherine Ashton.

Zarif and Ashton, who acts on behalf of the six world powers, will lead this week's negotiations. They were expected to meet over dinner on Monday evening.