Iran's senior negotiator said the nuclear offer that Tehran presented to world powers in Geneva on Tuesday did not cover snap inspections of its atomic facilities.
"It does not exist in the offer," said Abbas Araghchi, quoted by state news agency IRNA, after being asked if the additional protocol to the nuclear Non-Proliferation Treaty (NPT) allowing unannounced inspections was included in the proposal.
The additional protocol allows reinforced and unannounced inspections of a country's nuclear facilities by the International Atomic Energy Agency and requires that information be provided on all activities regarding the nuclear fuel cycle.
As it stands now, Iran is only obliged to inform the IAEA three months ahead of transferring fissile material into the nuclear site.
Iran, a signatory of the NPT, voluntarily implemented the additional protocol between 2003 and 2005 but ceased to apply it after its nuclear case was sent to the United Nations Security Council.
Last month, US Secretary of State John Kerry said acceptance of the additional protocol by Tehran would help to resolve Iran's decade-long nuclear standoff.
"They could immediately sign the protocols, the additional protocols of the international community regarding inspections," said Kerry.
And Ali Akbar Salehi, head of Iran's Atomic Energy Organisation, said Iran was ready to remove ambiguities about its nuclear programme by "using every treaty, regulation and mechanism at the international level".
He did not rule out an eventual ratification of the additional protocol, but said Iran would expect in exchange that world powers recognise its nuclear rights under the NPT and IAEA charter.