Russia's state-controlled energy company Gazprom said it filed a lawsuit against Ukraine in Stockholm arbitration court.
Gazprom said it wanted to recover the £2.7 billion ($4.5 billion) Ukraine owes it for its gas supplies.
Talks between Ukraine and Russia over their ongoing gas pricing dispute have ended with no deal reached, a spokesman for Russian producer Gazprom said.
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Rain across central Britain with longer, intense downpours with thunder in places this evening. A lucky few will stay sunny and dry.