It all sounds like the Churchill Falls dispute between Newfoundland and Quebec, as reported in The Globe:

Russia's state-controlled natural gas monopoly on Monday accused Ukraine of diverting about $25-million (U.S.) worth of Russian gas intended for other European countries, a day after Moscow halted deliveries to Kiev in a price dispute...Gazprom supplies about one-quarter of the gas consumed in Europe. Most of that goes through pipes that cross Ukraine and the dispute has raised worries of widespread supply disruptions throughout much of the continent.