MOSCOW, Oct. 28 (Xinhua) -- Russian presidential aide Sergei Prikhodko said on Wednesday that sanctions against Iran are highly unlikely in the near future, Interfax news agency reported.

    "The introduction of sanctions against Iran is unlikely in the near future," Prikhodko was quoted as telling reporters.

    But the use of sanctions is "unavoidable" in some cases, Prikhodko said, referring to Russian President Dmitry Medvedev's remarks that sanctions are not very effective, but sometimes "we are forced to impose sanctions."

    "This formula is still valid," the Kremlin official said.

    Western powers suspect Iran of attempting to build nuclear weapons, but Tehran says its nuclear program is aimed at generating nuclear energy for civilian purposes. The UN Security Council has so far levied three sets of sanctions on Iran over its nuclear programs.

    Prikhodko also said Russia and the United States have made considerable progress on a new nuclear arms reduction treaty.

    A more favorable atmosphere has been formed thanks to U.S. President Barack Obama's decision to scrap the Bush-era missile defense plan, although some differences remain, he said.

    The Strategic Arms Reduction Treaty (START-I), signed in 1991 between the Soviet Union and the United States, obliges both sides to reduce their nuclear warheads to 6,000 and delivery vehicles to 1,600.

    Russian and U.S. negotiators have held several rounds of nuclear arms talks in a bid to work out a replacement for the START-I before it expires this December.