Ronnskar, Boliden's biggest production unit, halted output on June 13 due to safety reasons after fire destroyed its cell house in Sweden.

"For the time being we cannot say exactly when production will be resumed, we aim to within the next couple of weeks," Boliden said in an emailed statement.

Boliden declined to comment on the amount of deliveries affected by the force majeure, or unexpected circumstances that prevent a business from meeting contract obligations.

Prices for copper on the London Metal Exchange (LME) were up 0.6% at $8,606 per metric ton by 1500 GMT. The metal, used in the power and construction sectors, touched $8,634, its highest level in more than five weeks earlier on Friday.

The smelter produced 218,000 metric tons of copper in 2022.

A prolonged suspension of Ronnskar could tighten copper supplies at a time when only one-third - 30,250 metric tons - of the copper inventories in LME-registered warehouses are located in Europe.

Copper inventories in warehouses monitored by the Shanghai Futures Exchange fell 20% to 61,090 metric tons this week.

(Reporting by Pratima Desai and Polina Devitt in London; Editing by Alex Richardson and Matthew Lewis)