The foreign minister said internal differences would not justify any failure on the part of the United States to meet its international obligations under any final deal with Iran on Tehran's nuclear program.
"According to international law, internal disagreements do not exempt countries from fulfilling their obligations and this is the basic framework we consider important," Mohammad Javad Zarif was quoted by IRNA as saying.
"As we have said from the start, the US administration is considered responsible for implementing the deal and its domestic problems and disputes have nothing to do with us and with the implementation of the deal."
He made the remarks on Sunday upon arrival in New York to attend the 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).
Iran and the major powers, which have been negotiating to reach a resolution of the long-running dispute over Tehran's nuclear work, released a joint statement on April 2 in Lausanne to announce an agreement on the outline of a final deal whose details are set to be finalized by the end of June.
US President Barak Obama was forced to agree to a bill giving the Republican-dominated Congress the right to have a say on the prospective deal with Iran. Before conceding to the bill, the White House had managed to get the lawmakers to soften it.
"We expect officials of the US administration to provide explicit explanations on the issue," Zarif said.
"We want to hear their explicit explanations about their internal differences and the possible impact these differences may have on the implementation of the deal."
***Deal, Sanctions Not Compatible
Commenting on the contents of the prospective deal, the chief negotiator said, "We have repeatedly said a deal and sanctions are not compatible."
"We have also frequently pointed out that based on the framework agreed in the Lausanne talks, sanctions should be lifted simultaneously with the implementation of the deal and the UN Security Council resolutions should be terminated through issuing a new resolution."
The joint statement said, "The EU will terminate the implementation of all nuclear-related economic and financial sanctions and the US will cease the application of all nuclear-related secondary economic and financial sanctions, simultaneously with the IAEA-verified implementation by Iran of its key nuclear commitments."
A provision of the statement on the termination of the Security Council resolutions said, "A new UN Security Council Resolution will endorse the JCPOA (Joint Comprehensive Plan of Action – the official name of the final pact), terminate all previous nuclear-related resolutions and incorporate certain restrictive measures for a mutually agreed period of time."
"What has been agreed on in the Lausanne talks must be recorded in a binding document in the final stage (of negotiations) to go into effect after being signed by the two sides," Zarif added.
The foreign minister and his US counterpart John Kerry were scheduled to meet Monday on the sidelines of the review conference as part of a new round of negotiations aimed at continuing the process of drafting the final deal, which started in the Vienna talks last week.
