The company says it has begun pumping additional fuel through its pipelines to compensate for what it calls Ukraine's "theft" of transit gas meant for Europe.
Gazprom Deputy Chairman Aleksandr Medvedev made the announcement in Moscow, but he said the current situation could not continue permanently.
"By tomorrow evening (Tuesday), we will restore full supplies to Europe in accordance with our contracts. However, I would like to stress that the current situation under which Ukraine continues to steal gas from the pipeline and we continue to supply European consumers cannot go on forever," Medvedev said.
He went on to make it clear that the blame for any future drop in European delivery levels would be on Ukraine.
"Maintaining this situation would be the same as encouraging Ukraine to steal our gas on the way to Europe. So all of our European partners have been warned that we are doing the maximum to maintain gas supplies to Europe. The responsibility for a possible break in supply lies completely with the Ukrainian side."
Yesterday, Russia's state-controlled gas monopoly Gazprom cut off domestic gas supplies to Ukraine after the two sides failed to agree on prices for 2006.
Germany, Austria, Slovakia, France, and Italy -- among others -- say their supplies of Russian natural gas coming via Ukraine have dropped by 25 to 40 percent since then.
A spokesman for EU foreign policy chief Javier Solana today called for a quick "negotiated solution" to the standoff between Ukraine and Russia.
(agencies)