A leak on a pipeline carrying oil from Russia to Europe has stoked concerns about energy security, while European Union ministers work on proposals to address the fuel crisis facing the continent heading into winter.

Poland revealed they had detected the leak in one of the Druzhba pipelines on the main route for oil to Germany, but believe it was probably caused by an accident.

The Nord Stream gas pipeline that serves Germany is currently out of action after a leak last month that has been blamed on sabotage by Russia and the West.

The discovery of the leak in Poland, which operator PERN said it found on Tuesday evening, comes as Europe faces a severe energy crisis in the aftermath of the conflict in Ukraine which has cut supplies of gas in a continuing stand-off.

"Here we can talk about accidental damage," said Mateusz Berger, Poland's top official in charge of energy infrastructure. He added there were no grounds to believe the leak was caused by sabotage.

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PERN said in a statement that at this point the exact causes of the leak were unknown. It was detected in a section of the pipe around 70 kilometers from the central Polish city of Plock.

A German economy ministry spokesperson insisted their oil supply was secure and the Schwedt and Leuna refineries were still receiving oil via the Druzhba pipeline Freundschaft 1 via Poland.

The spokesperson admitted the ministry was watching the situation closely and both refineries had been increasing their on-site stocks in recent weeks as a precautionary measure.

The Druzhba oil pipeline, whose name means "friendship" in Russian, is one of the world's largest, supplying Russian oil to much of central Europe including Germany, Poland, Belarus, Hungary, Slovakia, the Czechia and Austria.

"The main action (we are taking) is to pump out the liquid and locate the leak and stop it," a fire brigade spokesman told Polish TV. "When the pressure decreases, the leak will stop and allow us to reach the leak."

PERN said the second line of the pipeline, and other elements of PERN's infrastructure, were working as normal.

Russian oil imports into the EU and the UK fell 35 percent to 1.7 million barrels per day (bpd) in August from 2.6 million bpd in January. However, the EU was still the biggest market for Russian crude, according to the International Energy Agency.

The UK has already stopped importing Russian crude, with the EU banning imports from December in an attempt to strip the Kremlin of revenue to fund the conflict.

The ban will most likely create a shortage of oil due to a general lack of spare crude volumes in the world.