Russia's President Dmitry Medvedev ordered the state-controlled gas monopoly to cut gas supplies to ex-Soviet neighbour Belarus over its debt for Russian natural gas supplies.
Mr Medvedev's order today follows his warning to Belarus last week to start paying off its 200 million US dollar debt or face cuts.
Belarus challenged the Russian claim and refused to pay. Mr Medvedev ordered the head of gas giant Gazprom to implement cuts starting today.
Belarus' economy has been struggling to cope with rising Russian natural gas prices and excise hikes on Russian oil imports.
Belarus President Alexander Lukashenko insisted that Russia provide it with cheap oil and gas as part of the customs union deal to come into force on July 1, but Moscow rejected the demand.