The company sold the 730,000 barrel cargo to a Russian trading house at around $4.50 a barrel to Dubai quotes, he said, although this could not be confirmed.

In its previous ESPO tender, TNK-BP sold an April loading parcel at a premium of around $3.40 a barrel to Dubai quotes, probably to Japanese refiner JX Holdings, traders said at the time.

Last week, top Russian oil producer Rosneft sold two cargoes of ESPO Blend crude via tender at a record premium of $4.75 a barrel to Dubai quotes as Libya's supply outages boosted values of sweet grades in Asia.