A leak has been found on a pipeline serving as the main route for Russian crude oil transported to Germany, authorities said Wednesday. The problem was detected in Poland by Polish operator PERN, which said it found the leak Tuesday evening on the Druzhba pipeline that originates in Russia. The cause of the leak was not immediately established and firefighters were working at the site of the spill, PERN said. News of the leak comes after sabotage was suspected as the cause of leaks last month on the Nord Stream 1 and 2 gas pipelines under the Baltic Sea. The Russian-built pipelines had been at the center of a bitter energy war that has been escalating between the Kremlin and European countries since the beginning of the war in Ukraine.