Kazakh state oil and gas company KazMunaiGas said Thursday that oil supplies from Russia to Kazakhstan have been restricted, a month after Russia limited oil to refineries in Belarus.

KazMunaiGas subsidiary Trade House KazMunaiGas said in an emailed reply to Dow Jones Newswires that the talks on the oil-supply cuts were being held but provided no further details.

A spokeswoman for KazMunaiGas said that "there hasn't been any official notification on this issue from the Russian side."

A person at a Russian oil company, who requested anonymity, said the dispute between Russia and Kazakhstan resembles the spat with Belarus, when oil supplies were reduced during negotiations over customs duties on Russian crude. The curtailment in oil supplies to Kazakhstan, however, are less vital because Kazakhstan has enough oil to feed its refineries and exports its own hydrocarbons, the person said.

Russia, Kazakhstan and Belarus have agreed to form a customs union to ease the flow of goods among the former Soviet countries. The trio is currently hammering out details of the union.

Company Web site: www.thkmg.com

-By Kadyr Toktogulov, Dow Jones Newswires; +7 701 726 4327, kadyr.toktogulov@dowjones.com

(Alexander Kolyandr in Moscow contributed to this report)