That is the highest level of enrichment acknowledged by Iran and one that experts say could be turned into warhead grade in a matter of months.
In an interview with the Kuwaiti news agency KUNA that was released by the Foreign Ministry on Tuesday, Sergey Lavrov said that "for the first time in many years" there are encouraging signs in international efforts to resolve the Iranian nuclear dispute.
He said Iran has confirmed that it is ready to halt production of uranium enriched to 20 percent. He did not give details, but said the sextet of international negotiators should make "substantial reciprocal steps."
In the interview, Lavrov did not say which Iranian officials had expressed the willingness to pull back on enrichment and when the position was made known. The interview was released a day after Iran's president-elect Hasan Rowhani promised a "path of moderation" that includes greater openness on Tehran's nuclear program and overtures to Washington.
But Rowhani also said Iran would not halt uranium enrichment. That could indicate Iran would be satisfied to continue the relatively low-level enrichment needed for fuel rods in the reactor at its atomic energy plant in Bushehr.
Over the past year, the international community has imposed heavy economic sanctions on Iran, hoping they would be so painful that the Islamic republic's clerical regime would slow its nuclear program.
"The international community should respond appropriately to the constructive moves by the Iranian side, including step-by-step halting and cancellation of sanctions -- unilateral ones and those enacted by the UN Security Council," Lavrov said.
Any halt in 20-percent enrichment would be a significant concession by Iran, but it would not necessarily mean any drawdown in enrichment capabilities; the labs could concentrate on lower-grade fuel. The 20-percent enriched material is used in Iran's research reactor and is many steps closer to warhead-grade uranium than the type used in energy reactors.