There were no signs of progress towards an agreement according to the union, Reuters reported on the weekend.
Sindicato No 1 has organised an extraordinary assembly for its members at 9pm last night and 9am this morning, to inform on the state of the negotiations.
The prospect of a strike for the second year in a row grew last week with the sides failing to reach agreement and the negotiation period ends on July 24.
The workers ended a six-week strike last year, that had impacted the global copper market, by invoking an 18-month extension to their existing agreement.
This agreement with Union No 1 will expire on August 1 and negotiations for a new agreement were in progress, BHP said in its operational review last week.
Escondida's copper production for the year to June 30 was 57% higher than the previous year, at 1.2 billion tonnes, reflecting a full year of production and the start-up of the Los Colorados extension project.