(Adds comments from mine president, background on mine and...

(Adds comments from mine president, background on mine and strike)

Negotiations between BHP Billiton (BHP) and striking workers at its Escondida copper mine in Chile have failed, and the company will try to restart operations, mine President Marcelo Castillo said on Thursday.

"We haven't come to the agreements that both sides wanted," Castillo told reporters in the city of Antofagasta. " ... The managers (at the negotiating table) are returning to their work posts to focus on normalizing operations."

Escondida's 2,500-member union was not immediately available to comment but will hold a news conference later on Thursday. The deposit is the world's largest copper mine, producing slightly more than 1 million tonnes in 2016, or about 5 percent of global output.

Castillo added in his remarks that BHP was still considering how it would restart operations. Options include using non-union contractors or unionized workers who opt to break the picket by taking the company's last official offer.

The company will also evaluate the Chilean labor code's rarely used Article 369 option, which would allow miners to work under the previous contract for 18 months, if miners propose the idea, Castillo added.

Under Article 369, the previous wage agreement signed four years ago would be extended by 18 months. At the end of that period, both sides would again need to try to reach a new agreement.

"Having collective talks in 18 months ... would require us to revise our plan, our operating model, our structure in order to allow us to make our mining business viable," Castillo said.

The union at BHP's Escondida in Chile, the world's largest copper mine, has been on strike since Feb. 9 in the longest work stoppage in Chilean mining in decades.

The strike has halted production, sending global copper prices CMCU3 higher amid supply concerns.

Escondida is majority-controlled by BHP with minority participation by Rio Tinto (RIO) and Japanese companies including Mitsubishi Corp <8058.T>.