BEIJING, Jan. 8 (Xinhua) -- Russia cut off all natural gas supplies to Europe through Ukraine Wednesday, which has greatly affected gas supplies to Europe.

    Russia is the world's largest natural gas producer and exporter. A major consumer of Russian gas, Europe imports one fourth of its gas needs from Russia. Russia has built a number of pipelines delivering gas produced in Siberia and Central Asia to Europe.

    Currently, there are three major export routes for Russian gas to be transported to Europe. One consists of pipelines going through Ukraine. After Ukraine, they extend westward to Slovak, the Czech Republic, Germany and Austria, southward to Moldova, Romania and Bulgaria.

    The second route, known as the Yamal-Europe pipeline which bypasses Ukraine, runs to Germany via Belarus and Poland. The third one, the Blue Stream pipeline, passing through eastern Ukraine, goes underneath the Black Sea and leads to Turkey.

    Russian gas supplies to France, Britain, Italy and other European countries are being delivered through gas pipeline networks of these countries.

    However, due to historical and geographical reasons, all of Russia's pipelines leading to Europe, except for Yamal-Europe, run through Ukrainian territory. Each year, about 80 percent of Russian gas to Europe, or roughly 120 billion cubic meters, flows through Ukraine.

    Apart from Ukraine, Russian gas can also be transported through Yamal-Europe, although the pipeline's current capacity is just 30 billion cubic meters annually. The Blue Stream pipeline has a designed annual capacity of just 16 billion cubic meters.

    In recent years, Russian gas supplies to Europe have often been affected as a result of rows between Russia and Ukraine over prices and transit fees. In view of the situation, Russia has begun to seek alternative gas routes, including the Nord Stream Pipeline, which runs to Germany via the Baltic Sea, and the South Stream pipeline, which runs underneath the Black Sea and leads to Bulgaria.

    These pipeline projects would not only help diversify Russia's export channels, but would also spare it the burden of transit fees.

    However, as the pipelines are either still under construction or just in the planning stages, Ukraine will remain a key transit point for Russian gas supplies to Europe for the next few years.

    In the wake of the flare-up of the latest Russian-Ukrainian gas row, Russia has promised to guarantee gas supplies to Europe through other channels. However, in the absence of swift effective measures, European countries this time are likely to bear much of the impact of the Russian-Ukraine gas crisis.