Century Aluminum Co said in a news release on Tuesday that Logan Kruger, its Chief Executive since December 2005, resigned and filed a lawsuit against the aluminum producer, alleging a breach of contract and wrongful termination.
The company said the claims were without merit and it intends to "vigorously defend itself against them," without elaborating.
Requests from the primary aluminum producer for addition information about Kruger's termination went unanswered.
Century Aluminum named Chief Financial Officer Michael Bless as acting president and chief executive, replacing Kruger.
Kruger had been Century Aluminum's CEO, while Bless was finance head since January 2006 and will retain the role of CFO.
The company's shares have fallen 29 percent this year to close at $11.08 on Tuesday on Nasdaq.
"We are continuing our efforts to return the Hawesville smelter to stable operations, and remain on track to reach full capacity during the first quarter of 2012," Bless said in the news release.
In August, Monterrey, California-based Century said it planned to restart the idled fifth of five potlines at its Hawesville, Kentucky aluminum smelter by year end, lifting production at the facility to its 244,000 tonne-per-year capacity.
Century curtailed the potline in March 2009 to contain plant costs, while faced with depressed aluminum prices. It had previously planned to bring the potline back online during the first quarter of 2011, adding about 4,370 tonnes a month of production.
About the company's Iceland smelter, Bless added: "Grundartangi's performance continues to be excellent and discussions continue in several key areas of the Helguvik project as we await the arbitration decision with one of our power suppliers."
Last month, Century Aluminum reported a net loss of $6.6 million ($0.07 per basic and diluted share) for the third quarter of 2011.
At that time, it said discussions continued in several key areas of the Helguvik, Iceland project, and it was waiting for a decision from an arbitration panel regarding its contractual dispute with one of the power suppliers.
In August, Century said, the Helguvik smelter should produce its first 90,000 tonnes of aluminum by early 2014, or about 24 months after construction begins in early 2012. But it warned that timeline was contingent on garnering an adequate power contract.
Prior to joining Century, Bless previously served as Chief Financial Officer of Rockwell Automation, Inc and was an investment banker at Dillon, Read & Co for over 10 years, the statement said.