A sign reading Nord Stream 2 Committed. Reliable. Safe. hangs above a painted map of the Nord Stream 2 pipeline from Russia to Germany at the natural gas receiving station in the Lubmin industrial estate in Lubmin, Germany, Nov. 16, 2021. AP
"PERN's technical services on Saturday restored the full functionality of the damaged line of the pipeline, which supplies crude oil to the company's German clients," the operator said in a statement.
"An investigation into the cause of the leak is ongoing," it added.
The company had earlier said preliminary checks indicated that the leak was probably accidental.
The incident came after four leaks damaged the undersea Nord Stream gas pipelines from Russia to Germany.
The Druzhba leak -- on an underground segment of one of two lines -- was detected on Tuesday near the village of Zurawice in central Poland.
The pipeline mainly supplies the Schwedt and Leuna refineries in Germany.
The Druzhba (Friendship) pipeline network was started in the 1960s and pumps oil from the Urals to Europe through a northern branch via Poland and a southern branch via Ukraine.