Iran's chief nuclear negotiator Ali Larijani warned in Tehran on Sunday that Iran would resume a large-scale uranium enrichment if its nuclear case was referred to the U.N. Security Council.

"If the nuclear dossier is referred to the U.N. Security Council, Iran will have to resume uranium enrichment," Larijani told reporters at a press conference.

Vowing not to suspend small-scale enrichment work as required by the European Union (EU) and Russia, Larijani said "Nuclear technology is one of Iran's sovereign rights which can never be abandoned."

Larijani's comments came one day before a key meeting of the International Atomic Energy Agency (IAEA) board of governors.

The U.N. nuclear watchdog adopted a resolution last month to report Iran's case to the U.N. Security Council, but called on the powerful U.N. body to withhold punitive actions until the agency's meeting on March 6.

It has been viewed that the IAEA resolution in February just posed a gesture aimed at pressing Iran to be more cooperative, and the meeting on Monday will be decisive for officially referring Iran's nuclear case to the U.N. Security Council.

The Washington Post reported on Saturday that the United States, preparing to take Iran's case to the U.N. Security Council next week, is seeking a 30-day deadline for Tehran to halt its nuclear program and cooperate with international inspectors.

Earlier Sunday, Iranian Foreign Ministry spokesman Hamid-Reza Asefi said it was possible for Iran to reach an agreement on its nuclear program with the EU or Russia "in the coming few hours".

"Anything is possible," he told reporters at his weekly news briefing, warning that a further involvement of the U.N. Security Council in the Iranian nuclear issue would be negative to the solution to the dispute.

"Tomorrow will be crucial for the IAEA, for a big test is confronting the agency, by which it will show how it defends its own authority and credibility by securing its members' rights. We hope the IAEA will avoid adopting political decisions," Asefi stressed.

Asefi also accused the United States of taking double-standards when dealing with different countries on nuclear issues, citing the recent accord of nuclear cooperation between the United States and India.

The tension over Iran's nuclear issue came after Tehran resumed nuclear fuel research work on Jan. 10 and the crisis escalated as Iran disallowed IAEA's snap inspections and resumed small-scale enrichment work, a retaliative move against IAEA's February resolution.

Uranium enrichment is a key step for constructing nuclear fuel cycle, but highly enriched uranium can be used for building nuclear weapons.

Echoing the U.S. accusation that Iran is seeking nuclear weapons, the EU, the longtime but recently-frustrated broker of the Iranian nuclear issue, holds that Tehran's full mastery of nuclear fuel cycle technology will lead to military usage.

Under EU's persuasion, Iran had suspended uranium enrichment for more than two years, which Tehran defined as a voluntary move subject to withdrawal.

Iran insists that its nuclear program is completely peaceful, vowing not to give up its legal rights.