(Reuters) -Freeport-McMoRan said on Tuesday it plans to restore production at Indonesia's Grasberg copper and gold mine by July after a fatal incident forced operations to halt two months ago.

Seven workers were killed when roughly 800,000 metric tons of wet mud flooded the Grasberg Block Cave, one of the mines at the complex, on September 8.

Grasberg is the world's second-largest copper mine and largest gold mine, a key asset for Freeport as demand for the red metal rises with the expansion of electric grids, renewable power and electric vehicles. The prolonged disruption has been closely watched by metals markets concerned about tightening supplies.

"While the incident was unprecedented in our history and with no indications of human error, we are humbled by this tragedy and resolve to use the learnings to address the confluence of factors and conditions that led to the event," Chief Executive Kathleen Quirk told investors on a conference call. The Phoenix-based company last month posted better-than-expected quarterly profit but had delayed discussing the results in the wake of the disaster until Tuesday.

The disaster was caused by mud that breached a previously undetected hole in the mine's retired open pit and rushed into a zone where a two-person electrical crew and a five-person boring crew were working. Mud reached that area in minutes, executives said during a detailed discussion of their investigation. The company said it is cooperating with Indonesian officials.

2026 COPPER AND GOLD OUTPUT SEEN MATCHING 2025

Under the phased restart plan, the company expects PT Freeport Indonesia's combined copper and gold output in 2026 to be roughly in line with 2025 levels, at about 1 billion pounds of copper and 900,000 ounces of gold. PT Freeport Indonesia owns Grasberg, with most of that company controlled by Jakarta at 51.2% and the remainder controlled by Freeport, which also operates the mine.

The company expects production to increase through 2026 and 2027, with average annual volumes of around 1.6 billion pounds of copper and 1.3 million ounces of gold expected for 2027-2029.

Freeport shares gained 4.5% to $40.75 in midday trading.