The trader's loss of lucrative business this month via the Soviet-built Druzhba pipeline is a sign of shifting alliances in the export of Russia's Urals blend, one of the world's largest and most stable streams of crude oil.
Souz is the second home-grown trade house with ties to Russian tycoons to be dislodged from an entrenched position in the export of oil after Gennady Timchenko's Gunvor, which once handled as much as 40 percent of seaborne Urals crude.
Summa is the vehicle of Ziyavudin Magomedov, a port and construction magnate who controls the largest shareholding in Russia's main port group, Novorossiisk Commercial Sea Port , together with Transneft, the Russian pipeline monopoly.
In January, Hungary, Slovakia and Poland, whose refiners were longtime buyers of Russian crude oil delivered by Souz via the Druzhba (Russian for "Friendship"), switched to other suppliers. Souz has shipped no crude to those destinations this month, several sources told Reuters.
Souz also lost a tender to buy 140,000 tonnes of Urals crude oil from Bashneft to be shipped from Novorossiysk at the end of January.