* Some 600,000 tonnes of tainted oil remain unsold
* Glencore hardest hit among Russian oil buyers
By Olga Yagova, Vladimir Soldatkin and Dmitry Zhdannikov
MOSCOW, Aug 21 (Reuters) - BP and Glencore are struggling to sell around 600,000 tonnes of tainted Russian oil more than three months after the contamination was discovered, according to six trading sources.
Russia's oil industry was plunged into a crisis in April after about 5 million tonnes of oil for export was found to be contaminated with organic chloride, a chemical used to help boost oil extraction but which can damage refining equipment.
Exports through the Druzhba pipeline that transports oil to Germany, Poland, Hungary, Slovakia, the Czech Republic, Ukraine and Belarus were halted. The Baltic port of Ust Luga loaded some 15 cargoes or 1.5 million tonnes of the contaminated oil for Western buyers.
At least 6 cargoes that sailed from Ust Luga remain unsold, according the trading sources. Glencore is stuck with 500,000 tonnes in one very large crude carrier (VLCC) Amyntas and two smaller tankers - Searanger and Searuby, according to the sources and Refinitiv Eikon vessel tracking system.
BP has tried to sell its cargo Fsl Shanghai at a tender earlier this month but failed, according to the same traders. BP and Glencore both bought the oil from Russian state oil major Rosneft.
BP and Glencore declined to comment. Rosneft did not respond to a Reuters request to comment.
They cannot claim compensation until they sell the oil.
"You can't file a claim against Russia until you have actually sold your oil and counted your losses," one of the trading sources said.
President Vladimir Putin said in April oil contamination had damaged Russia's image as a reliable supplier. Transneft and Rosneft have been at loggerheads over efforts to resolve the situation.
The oil was transported by pipeline monopoly Transneft, which said it was ready to pay compensation to Russian shippers which in turn would pay compensations to overseas buyers.
Transneft and the Russian Energy ministry did not respond to Reuters requests to comment.
So far, Transneft has only agreed to pay $15 per barrel in compensation, or roughly a quarter of the cost of the oil, to Kazakh oil producers, whose barrels got contaminated while en route to Western markets.
"Many buyers of Russian oil believe $15 per barrel won't be enough," a trading source in a major said.
Some consumers who received tainted oil consider $30 per barrel as reasonable compensation, two traders involved in the discussions said.
Several refiners, including Total's Leuna in Germany, had to temporarily suspend refining of Russian oil because of fears of damaging refining equipment.
Another source with a large Western buyer said consumers would most likely file claims in the autumn when they finally manage to refine the dirty oil.
Oil firms have to blend one barrel of tainted oil with as much as 10 barrels of clean oil to reach required quality standards and avoid damaging equipment, sources said.
Total, for example, offloaded its two tankers with dirty oil in Rotterdam and Lithuania for storage and blending and further refining.
Russian oil supplies along the Druzhba pipeline to Germany, Poland, Hungary, Slovakia and the Czech Republic have resumed in July after weeks of severely reduced flows.
Russia exported 24% less oil to Germany in the first six months of 2019, year-on-year, due to contamination although it still remained Germany's top crude supplier.
Some refiners like Total's Leuna and Poland's PKN Plock are blending tainted oil with cleaner barrels and are refining it.
Rosneft's Germany's refinery Schwedt has refused to take dirty oil, according to traders. Rosneft declined to comment.
Belarus has finished full clean-up of its system after Transneft pumped some 2 million tonnes of dirty oil back to Russia, Transneft and traders said.
Transneft now needs to dilute the oil with cleaner supplies to domestic refineries and export destinations.
The pipeline monopoly has also yet to sign final compensation documents with Kazakh producers to start repaying fees of $15 per barrel, traders said. (Writing by Dmitry Zhdannikov. Editing by David Evans and Jane Merriman)