The U.S. attempts to link nuclear arms reduction talks to possible sanctions against Iran are unacceptable, a Russian Foreign Ministry official said Tuesday.

"We believe that such a linkage is totally baseless. No trading is acceptable on these two issues, which are so different in substance and in format," the unnamed official told the Interfax news agency.

Russia will not toughen sanctions against Iran in exchange for a new nuclear weapons deal with the United States that would replace the expiring Strategic Arms Reduction Treaty (START I), he said.

"We see no reason to link these issues, let alone to expect that Russia would agree to toughen sanctions against Iran ... in the talks with the United States on further reductions of strategic offensive weapons," the official said.

Russian President Dmitry Medvedev and U.S. President Barack Obama signed a framework document in Moscow on July 6 on further reductions and limitations of strategic offensive arms.

The document stated that each country plans to cut nuclear warheads to 1,500 to 1,675 "within seven years to come."

START I, signed in 1991 and due to expire in December, places a limit of 6,000 strategic or long-range nuclear warheads on each side and allows the inspection of weapons.

A subsequent Moscow treaty signed in 2002 called for reducing nuclear warheads to between 1,700 and 2,200 by the end of 2012, but made no provision for verification.

Obama during his visit to Moscow also accused Iran and the Democratic People's Republic of Korea (DPRK) of pursuing nuclear weapons, warning that a nuclear arms races would endanger regional and global security.

A planned American missile defense system in Europe is widely regarded as an obstacle to a new START deal between the U.S. and Russia.

Washington said the planned shield was targeted against "rogue states" like Iran rather than Russia, while Moscow views the proposal as a major threat to its national security.

(Xinhua News Agency July 14, 2009)