TORONTO – Lundin Mining launched a hostile C$1.4-billion takeover bid for fellow Canadian base metals miner Nevsun Resources on Thursday, saying it had failed to convince Nevsun's board to agree to a friendly deal over the past nine months.

Cash-rich Lundin, looking to grow its production, has made five proposals to acquire Nevsun's large, high-grade Timok copper project in Serbia. With no appetite for Nevsun's Eritrean mine, it partnered with tiny mine developer Euro Sun Mining on its last buyout proposal for the whole company.

That offer, worth about C$1.5-billion, was rejected by Nevsun as too low.

Afterwards, Lundin said its best option was to make a direct offer to Nevsun shareholders to buy the whole company, noting significant political change in Eritrea.

Long-time rivals Eritrea and Ethiopia signed a peace accord this month, ending decades of hostility. Eritrea, formerly a province of Ethiopia, waged a 30-year war for independence and seceded in 1993. But relations soon soured and around 8 ,000 people died in a 1998-2000 war.

Nevsun also said this month that Lundin's C$4.75 offer undervalues the company and its assets. CEO Peter Kukielski noted a prefeasibility study which put the net asset value of Timok's upper zone at $1.82-billion.

Nevsun has said its special committee of independent directors and advisers would review any formal offer it received.

In a direct pitch to Nevsun shareholders with its C$4.75 per share all-cash offer, Lundin said that it became apparent over time that Nevsun’s management was unlikely to agree to a transaction despite multiple attempts to address its concerns. Nevsun shares closed Thursday at C$4.76.

"Each time we presented a proposal, the goal post changed," outgoing Lundin CEO Pa ul Conibear told analysts.

The offer is not subject to financing conditions and Lundin plans to fund the purchase using its $1.5-billion cash on hand and undrawn credit facility.

The offer, open until November 9, requires support from more than 50% of Nevsun shares and regulatory approvals.

Analysts have said it is unlikely another Canadian mid-tier miner would compete with Lundin's offer, but the quality and size of Timok could attract large global diversified companies, such as Rio Tinto .