This seems a very unreasonable hike to me. It would be like if you paid £1000 per month to rent your house, and then when your 1 year lease was up, the landlord damanded £2000 per month. I imagine a renter in that position might be reluctant to sing the next lease... and would hope to not be locked out on the 1st day the lease had expired.
Russia is being very unreasonable.
However, it will be interesting to watch this develop and see if Ukraine has paid or not (and hence which one of them is lying).
From reuter: uk.reuters.com/article/oilRpt/idUKL19444420090101 (copied below)
MOSCOW, Jan 1 (Reuters) - Russia's state controlled gas monopoly, Gazprom (GAZP.MM), wants to sell gas to Ukraine at $418 per 1,000 cubic metres (tcm) in 2009, more than double the price Kiev paid last year, RIA news agency quoted Gazprom CEO Alexei Miller as saying on Thursday.
"Gazprom will deliver gas to Ukraine at market prices of $418 per 1,000 cubic metres from January," Miller was quoted as saying, citing Ukraine's refusal to buy gas at $250 per tcm.
Last year Ukraine paid $179 per tcm. (Writing by Guy Faulconbridge; editing by Giles Elgood)