A dispute between Russia and Ukraine over gas prices has worsened.
The Russian company, Gazprom, says Ukraine has shut the last pipeline carrying Russian gas westwards across its territory.
The shut-down was confirmed by Ukraine, which said Russia cut off supplies first.
Seven European countries earlier reported they were receiving no Russian gas, while 12 more, including Germany, reported major reductions.
The EU depends on Russia for about a quarter of its total gas supplies, some 80% of which is pumped through Ukraine.
The row comes amid a cold snap across Europe that is likely to push up demand for gas. Outdoor temperatures are -10C or lower.
Russia began reducing gas volumes to Ukraine on 1 January. There was a similar disruption to supply in January 2006.