MOSCOW, April 6 - RAPSI. Sual Partners Group owned by Russian billionaire Viktor Vekselberg and his partners initiated a commercial litigation in a London court against Rusal, the world's leading aluminum producer, the EN+ company, the Glencore trading company, which owns a 8.75 percent stake in Rusal, and Rusal's owner Oleg Deripaska over an aluminum supply contract.

Sual Partners, owned by Viktor Vekselberg and Leonard Blovatnik, holds 15.8-percent stake in Rusal.

"Sual Partners initiated arbitration proceeding against EN+ , Glencore, UC RUSAL and Mr. Deripaska on April 4, 2012," a source close to Rusal's shareholders said.

The source also confirmed the media reports that the lawsuit is connected with the dispute between Rusal's shareholders, which arose following an illegal approval of long-term aluminum and alum earth contracts between Rusal and Glencore totally amounted to over $47 billion.

Sual's spokesman Andrei Shtorkh declined to give any comments referring to the confidentiality.

Rusal also refused to comment on the matter.

Viktor Vekselberg earlier resigned from the post of Rusal's board chairman and withdrew from the board. Vekselberg explained that he decided to resign as he disagreed with many decisions made by Rusal's management.

Rusal is the world's leading aluminum producer. It accounts for roughly 10 percent of the world's aluminum production and 10 percent of alum earth production. Rusal runs production assets in 19 countries. The company sales its products in Europe, North America and South-Eastern Asia.