MOSCOW, March 27 (RIA Novosti) - Russia has dismantled another six outdated Topol mobile missile systems under a major international treaty on strategic arms reductions, the Strategic Missile Forces said in a statement on Thursday.

"We scrapped six outdated Topol mobile systems between March 17 and 26," the statement said. "It is the first such procedure conducted this year."

The systems were based in the Udmurt Republic in eastern Urals.

The Strategic Arms Reduction Treaty (START-I) was signed by the United States and the Soviet Union on July 31, 1991, five months before the Union collapsed, and remains in force between the U.S., Russia, and three other ex-Soviet states.

Belarus, Kazakhstan and Ukraine have since disposed of all their nuclear weapons or transferred them to Russia, and the U.S. and Russia have reduced the number of delivery vehicles to 1,600, with no more than 6,000 warheads. The treaty is set to expire December 5, 2009.

Topol (SS-25 Sickle) is a single-warhead intercontinental ballistic missile (ICBM) approximately the same size and shape as the U.S. Minuteman ICBM.

The first Topol missiles became operational in 1985 and at the time the START I Treaty was signed, the Soviet Union had some 290 Topol ICBMs deployed.

Although the service life of the SS-25 was extended to 21 years after a series of successful test launches last year, the missile will be progressively retired over the next decade and be replaced by a mobile version of the Topol-M (SS-27 Sickle B) missile.

The Strategic Missile Forces press service said 36 mobile Topol ICBMs were dismantled in 2007 under close monitoring by U.S. inspectors.