The Polish operator of the Druzhba oil pipeline said it had fixed a leak that had caused part of the pipeline from Russia to Germany to be shut.
The operator, PERN, said in a statement on October 15 its technical services "restored the full functionality of the damaged line of the pipeline, which supplies crude oil to the company's German customers."
"An investigation into the cause of the leak is ongoing," it added.
The leak was detected on October 11 near the village of Zurawice in central Poland.
The company had said earlier that preliminary checks indicated the leak was probably accidental.
The German government said on October 12 that oil deliveries were continuing to two key refineries despite the leak.
The discovery of the leak came amid security concerns over Europe's energy supplies after the Nord Stream gas pipelines in the Baltic Sea recently sprang leaks that officials both in the West and Russia say were caused by sabotage.
Europe also faces a severe energy crisis as a result of Moscow's invasion of Ukraine, which has cut supplies to many countries.
The Druzhba (Friendship) pipeline network pumps oil from the Urals to Europe through a northern branch that runs through Poland and a southern branch that runs through Ukraine.