BP and Glencore are still trying to offload huge reserves of tainted Russian crude oil several months after problems were discovered.
The UK-listed giants have around 600,000 tonnes of the oil which they are struggling to sell off, several traders told Reuters.
A scandal erupted in April this year when authorities discovered around 5m tonnes of contaminated Russian oil, lined up for export to Europe.
The Druzhba pipeline was stopped, cutting off flows to Germany, Poland and Ukraine, among others.
The oil was found to have high levels of organic chloride, which helps boost extraction, but cannot be used in refining equipment.
Glencore is stuck with around 500,000 tonnes of the black stuff in three tankers, Reuters reported.
Meanwhile BP unsuccessfully tried to sell its oil at a tender.
It means that the giants will be unable to claim compensation as rules require them to sell oil before filing a case.
“You can’t file a claim against Russia until you have actually sold your oil and counted your losses,” one trader said.
Pipeline company Transneft has said it will pay compensation to the shippers who would pass it on to their customers.