The discovery of the leak in the main route carrying oil to Germany, which operator PERN said it found on Tuesday evening, comes as Europe is on high alert over its energy security in the aftermath of Moscow's invasion of Ukraine which has cut supplies of gas.
Polish Prime Minister Mateusz Morawiecki told Poland's state-owned radio broadcaster PR3 that it was too early to say whether the leak was accidental damage or caused by sabotage.
All potential causes of the leak were being considered, a spokesman for the Polish security services, Stanislaw Zaryn, told Reuters.
Reuters