Deputy Defense Minister Georgy Kondratyev was quoted by local reporters in Bendery, a town on the edge of the rebel region, as saying the contingent of 1,200 men would be cut to 600.
Kondratyev said the decision had been prompted by the calm situation and the high cost of the peacekeepers.
The Moldovan delegation in the commission had urged Moscow to keep at least 800 men, saying further cuts could shatter the military balance.
"The positions abandoned by Russian peacekeepers are gradually occupied by ... armed units of the Transdnestr region, which are not under the control of the commission," Moldovan Deputy Interior Minister Viktor Catan told Moldovan radio Thursday.
Transdnestr has expressed worry that the Moldovan army might attack the rebel region once Moscow cuts its forces.
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