REPUBLIKA.CO.ID, VIENNA/DUBAI - Iran expected to get a fifth installment this week of previously blocked overseas funds, a senior official was quoted as saying, a payment that would confirm Tehran's compliance with an interim deal with world powers to curb its nuclear program.

Separately, Iranian President Hassan Rohani said "tough issues" faced the Islamic Republic and the six major powers in negotiating a permanent accord to resolve the decade-old nuclear dispute but that it was still possible by a late July deadline.

"If it (the negotiation process) goes on with the same trend, the final agreement could be reached within six months," Rohani, seen as a pragmatist, was quoted by news agency Tasnim as saying at a meeting in a southeastern province late on Tuesday.

Rohani, whose election last year paved the way for a major thaw in ties with the West, was apparently referring to the goal of hammering out a long-term settlement before the six-month deal struck late last year expires on July 20.

"This means removal of sanctions and restoring financial relations with the rest of the world," he said, making clear Iran's aim to have sanctions that limit oil exports and make financial transactions difficult lifted as soon as possible.

Diplomats and experts say it will be difficult, but not impossible, to resolve the standoff over nuclear activities which Iran says are peaceful but the West fears may be aimed at developing nuclear weapons capability.

Western states want Iran to significantly scale back its nuclear program to make sure it cannot quickly make an atomic bomb. Iran has ruled out shutting any nuclear facilities.

Under the preliminary agreement that took effect on January 20, Iran will receive a total of 4.2 billion USD of blocked funds in eight payments over six months, if it lives up to its part of the deal designed to allay fears about its atomic aims.

It says it has already received four transfers in February and March, totaling some 2.1 billion USD. A fifth payment of 450 million USD was due on April 15, contingent on Iran having diluted half of its most sensitive stockpile of nuclear materials. Diplomats say Iran is meeting its commitments under the accord.

Deputy Foreign Minister Majid Takht-Ravanchi, a senior member of Iran's nuclear negotiating team, told the official IRNA news agency on Tuesday that the latest installment "was to be freed today".