The proposal came in a report released after talks run by a government mediator between the company and the United Steelworkers (USW) union.

While the union committed itself to the terms set out in the report, the company said the four-year labour deal proposed would leave it vulnerable to future possible simultaneous strikes at Voisey’s Bay and the other Vale mine at Sudbury, Ontario, where last year a five-year deal was concluded, ending a one-year strike.