Casablanca issued a statement saying it planned to continue to seek full control of Cliffs’ board and usurp CEO Gary Halverson through a proxy contest.

Cliffs said that to avoid the costly proxy contest, it had attempted to reach a settlement in the best interests of all its shareholders.

It claims Casablanca requested postponement of the record date for its annual meeting of shareholders.

To accommodate this request and continue negotiations, Cliffs said it indefinitely postponed the record date for its annual meeting scheduled for May 13.

However, Casablanca issued a statement condemning Cliffs for indefinitely postponing it.

"The board that owns virtually no shares and has presided over 80% value destruction is in our view showing its true colours by indefinitely postponing a shareholder vote and falsely suggesting that the delay was advocated by Casablanca. We look forward to engaging in a substantive dialogue with other Cliffs shareholders," the investment adviser said in a statement.

Cliffs again hit back, saying that chairman James Kirsch spoke on the phone with Casablanca chairman Donald Drapkin and CEO Douglas Taylor, with Drapkin “made the suggestion” that Cliffs postpone the record date for the meeting of shareholders.

Cliffs said it had offered to allow Casablanca to appoint two independent directors to its board, with a third to be negotiated between both companies.

Cliffs maintained that Casablanca’s representation was “entirely disproportionate” to its stake in the company and that it did not offer Cliffs’ shareholders a control premium.

In an open letter to Cliffs, the fund manager advocated that Cliffs create Cliffs International by combining its Bloom Lake iron-ore mine, in Quebec and Asia Pacific projects.

In January, Casablanca presented a rage of recommendations to Cliffs such as significantly cutting selling and divesting from infrastructure and other noncore assets.

Casablanca believes that implementing these recommendations would create substantial shareholder value and result in an implied valuation range, with a midpoint of $53 per Cliffs share, more than 2.5 times Cliffs’ current trading price.

Cliffs’ stock price has plummeted more than 80% since its high of $101.43 in mid-2011.