Poland, Germany, Ukraine, Slovakia and other countries halted Russian oil imports via the Druzhba pipeline last month after finding contaminants that could damage refinery equipment.

The ministry said it was still working to "normalise the quality indicators of oil in the Druzhba pipeline."

Poland's energy ministry said earlier on Friday that the suspension of crude deliveries via the Druzhba pipeline did not jeopardise its oil supplies.

Poland's number two refiner Grupa Lotos said late on Thursday that it was receiving supplies from the Russian coastal town of Primorsk and that it had its own reserves to maintain operations at its Gdansk refinery.

Trade sources said that also some oil tanks in Ust-Luga have already received normal quality crude with organic chloride content of below 10 parts per million (ppm), the latest tanker that loaded on Friday still had an organic chloride content 3.5 times above the norm.