Russian billionaire Oleg Deripaska's Central European Aluminum Company (CEAC) is suing Montenegro for 100 million euros ($140 million) over the failure of its aluminum plant there, Reuters reported. A statement issued in Cyprus, where the Russian company has its headquarters, CEAC said the case will heard in Vienna. The statement said Montenegro violated a 2010 settlement agreement, leading to the plant going bankrupt. In a separate statement, Montenegro's government denied any wrongdoing. Deripaska's company in 2005 bought a 58.7 percent stake in Kombinat Aluminijuma Podgorica (KAP), which in its heyday in the late 1970s had employed 5,000 people. In a debt for equity deal, the Balkan country's government took back half of that stake in 2009 and the arrangement was sealed in 2010. Deripaska is also co-owner and chief executive of Rusal , the world's biggest aluminium producer, which is feeling the effects of a weak aluminium price and the cost of maintaining net debt of around $10 billion. Read more.