Ukraine is pushing its own gas transit network as an alternative to the Nord Stream 2 pipeline from Russia to Germany, which has been constructed but not yet approved.
"In the entire history of Ukrainian transit, it did not happen once that it was cancelled because of any technical problems on the Ukrainian side," Serhiy Makohon, the head of the company operating the Ukrainian gas transit system, said in Kiev.
He added that two interruptions in 2006 and 2009 were solely due to Russian political moves.
Nord Stream 2 is intended to bring gas from Russia to Germany via the Baltic Sea, bypassing Ukraine.
Ukraine is very dependent on the billions in revenue from gas transit fees and now fears heavy losses.
Russian energy giant Gazprom is fulfilling the contract, which is valid until the end of 2024, with 40 billion cubic metres of transit per year, Makohon said.
But that is 30 per cent less than last year and 45 per cent less than in 2019, he said, adding that within those two years the system has not really deteriorated.
"We are ready to transport an additional 100 billion cubic metres of natural gas a year [to the European Union]."
However, if Russia stops its transit through its neighbour, Ukraine will have to either quintuple tariffs or pivot the gas transportation system to the domestic market, the head of the state-owned company said.
"We have expenses, and we cannot cover them at the expense of Ukrainian consumers."