Ukraine now controls less than half of Russia's gas transit to Europe, in a change to a system that existed for decades.
Once the route for two-thirds of Europe-bound gas from the east, the country ceded the position as Gazprom grew its transporting opportunities elsewhere.
About 42 percent of Gazprom's gas traveled through Ukraine in the first 10 days of this year, Interfax reported, citing data from domestic and European control rooms.
Gazprom built up its traffic via Belarus, where it took full control of the transit pipeline last year. With its partners, it also completed the second phase of the Nord Stream pipeline to Germany? under the Baltic Sea in November.
Ukraine's share of the transit to Europe stood at 63 percent in the first quarter of 2011, Interfax said. It slipped to 56 percent in the? first quarter of 2012.