The International Atomic Energy Agency (IAEA) on Monday confirmed that Iran had started enriching uranium to the 20-percent level at its Fordo plant.

“This step once again demonstrates the Iranian regime's blatant disregard for its responsibilities and that the country's growing isolation is self-inflicted,” Secretary of State Hillary Clinton said in a statement.

Clinton lamented that the construction of the new plant in Qom had been carried out secretly for three years.

“Iran only declared the Qom facility to the IAEA after it was discovered by the international community following three years of covert construction. Iran has announced it intends to consolidate and increase its production of uranium enriched to a near 20 percent level at this facility,” she said.

“There is no plausible justification for this production. Such enrichment brings Iran a significant step closer to having the capability to produce weapons-grade highly enriched uranium,” Clinton said.

The state secretary said Tehran’s statement that the decision was necessary to produce fuel for the Tehran Research Reactor (TRR) is “false.”

“We call upon Iran to immediately cease uranium enrichment and to comply with its international nuclear obligations. We also call on Iran to return to negotiations with the P5+1 [five permanent members of the UN Security Council plus Germany],” Clinton said.

Western nations suspect Iran, already under a few sets of international sanctions, of pursuing a secret nuclear weapons program but Tehran insists it needs nuclear power solely for civilian purposes.