TORONTO - Inmet Mining Corp. rejected Wednesday a hostile takeover offer worth $4.9 billion in stock and cash by First Quantum Minerals Ltd.

The company said its board of directors has determined the "highly conditional" offer is not in the best interest of its shareholders. However, it did not offer any details of the proposal.

"After reviewing the proposal with its financial and legal advisers, Inmet's board of directors has today notified First Quantum that it has declined to pursue the proposal," the company said in a brief statement.

Inmet also announced a shareholder rights plan, or so-called poison pill, a common tactic used to fend off hostile takeovers.

Under the proposal, First Quantum had offered $70 per share for First Quantum shares, half in cash and half in stock.

Inmet said the offer presented to the company Sunday followed an earlier unsolicited proposal from First Quantum of $62.50 per share.

Shares in Inmet were up $9.69 at $62.49 in trading on the Toronto Stock Exchange after the news was announced.

Earlier this month, Inmet denied a report suggesting the company was in talks regarding the potential sale to First Quantum.

Inmet said at the time it was focused on "building shareholder value by maximizing its operating assets and through the development of its Cobre Panama copper project."

Inmet recently dropped a hostile takeover bid of its own for Petaquilla Minerals Ltd. (TSX:PTQ) after it failed to win shareholder support.

In addition to Cobre Panama, Inmet has mines in Turkey, Spain and Finland.

Inmet and Lundin Mining (TSX:LUN) called off a proposed merger last year.