"This is very serious because the chairperson is the only member of the board defined as independent," Edström said in a company statement.
Edström argued that a move by Williams, together with the firm's other main shareholder Cukurova, to block an increase in the number of independent board members in the company indicates a lack of impartiality.
"For us, this is a very clear sign that he is not independent and impartial in relation to one of the major shareholders," she said, confirming that she was referring to Cukurova.
TeliaSonera maintains that Williams "clearly violated the law" by preventing the issue of board composition to be addressed at the company's annual general meeting.
The Swedish-Finnish firm company now intends to sue Williams in Turkey and possibly also in the US, since Turkcell is listed there.
TeliaSonera has long been embroiled in a dispute regarding Cukurova's stake in Turkcell.
At the heart of the dispute, which erupted in 2005, was a decision by Turkcell's previous majority owner, Cukurova, to sell the same Turkcell ownership shares twice, first to TeliaSonera, and then to Altimo.
Edström argued that despite the long dispute, TeliaSonera has no plans to sell off its stake in Turkcell.
"Turkcell is a first-rate company with good profitability and high potential. Turkey is a large market, and ownership creates value for us and for our shareholders. So we want to stay."
TeliaSonera has long argued that the number of independent directors on the board of Turkcell must be increased to meet the demands of both the US and Turkish financial services authorities.
TeliaSonera recently requested that the issue be addressed formally at the upcoming annual general meeting, but Turkcell's board rejected the request.
The board's position is reported to be in contravention of Turkish law which stipulates that a shareholder with more than 5 percent of the shares has a right to raise issues for discussion at the AGM.
TeliaSonera's currently controls 38 percent of Turkcell.