In a statement, Vestas said Deminor is basing its claim on an lawsuit initiated in the US in March 2011 by a pension fund who claimed the company issued false information regarding its revenue and earnings.
The claim is also issued against past and present board members, Bent Erik Carlsen, Jørgen Huno Rasmussen, Jørn Ankær Thomsen, Torsten Erik Rasmussen, Håkan Eriksson, Kurt Anker Nielsen, Freddy Frandsen, Ola Rollén and Ditlev Engel.
It also includes former CFO Henrik Nørremark who is under investigation over a deal undertaken in India without board approval.
According to Vestas, Deminor also states it will take Vestas to court unless it is paid within 10 days. In response, Vestas has said the claim has no merit and will not be accepted.
Earlier this year, Deminor failed in a bid to force Vestas to appoint a scrutiniser to examine recent business decisions by the board. It was voted down at the company's AGM by 89.5% of shareholders.
Following the defeat, Deminor partner Erik Bomans said the company is finalising a law suit that will be brought in the "next couple of weeks". He added: "We claim that Vestas has had a major shortfall of revenues versus its own guidance, especially in the year 2010, and that it has not correctly informed investors about it."