Iran will refuse any agreement on its nuclear capabilities if all outstanding issues are not treated as one package, Palestinian Al-Resalah newspaper reported the country's foreign minister as saying yesterday.
Meanwhile, the International Atomic Energy Agency (IAEA) asked Iran to give more details about its nuclear programme.
Speaking before members of the Council of Leadership Experts held in Tehran, Mohammad Javad Zarif said that all the outstanding issues must be resolved as one bundle.
He reiterated that if no agreement is reached, then this is because of America and not Iran, insisting that a comprehensive deal must lift all the sanctions which have been imposed on Iran for years.
After several rounds of negotiations in Switzerland, Iran and the P5+1 countries agreed to put together the basis for a potential deal. Zarif is expected to meet his American counterpart in Switzerland on Sunday.
Previously, the head of the US State Department John Kerry said that a meeting with Zarif last week achieved a considerable development, but said there was some "gaps".
Meanwhile, US State Department spokesperson Jennifer Psaki said that the coming weeks would be decisive regarding whether Iran is going to take difficult political decisions in order to reach a deal.
On Monday, Zarif dismissed a letter from 47 US senators warning that any nuclear deal will require Congressional approval, saying that it had "no legal value".
"We believe that the letter has no legal value and is propaganda," Zarif was quoted as saying by the Iranian media.
"The senators must know that under international law, Congress cannot change the content of the agreement," he said. "Any congressional action to prevent the implementation of any agreement will violate the international commitments of the [US] government."
"The world is not just in America," Zarif added.