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BOGOTA, Aug 31 (Reuters) - The largest workers union at the Colombian coal mine Cerrejon walked out on strike on Monday, the group said, after its members voted overwhelmingly to support the move following a collapse in contract negotiations.
Some 99% of members of the Sintracarbon union who voted on possible strike action earlier this month backed the walkout over arbitration.
"Despite the union's efforts to reach a negotiated agreement, we have determined to start the strike today from 03:15 in the afternoon," the union said in a statement.
"Cerrejon's arrogant and imperative attitude caused the failure of the meeting of today despite the mediation of the labor ministry," the union said, adding that it wants resolution not just to contract negotiations but to a disagreement over a new work schedule it calls "the death shift."
Cerrejon, owned equally by BHP Group BHP.AX , Anglo American AAL.L and Glencore GLEN.L , said in a statement it has a plan in place to manage the strike.
"In view of the strike announced by the union, we at Cerrejon have already implemented a contingency plan ... to protect our assets while operations shut down," company vice president Juan Carlos Consuegra said.
Sintracarbon had demanded a 6% salary increase in addition to health, education and housing benefits. Cerrejon offered an increase equal to inflation for 2020 and 2021.
Colombia had 3.80% inflation in 2019. The central bank expects inflation to end this year between 1% and 2%.
The union accuses Cerrejon of looking to cut costs by freezing, reducing and eliminating employee benefits.
Cerrejon employs more than 5,500 workers, including 4,600 union members.
The last strike at Cerrejon in February 2013 lasted 32 days.
Last year, coal prices fell to an average of $51.40 per tonne from $82.50 in the previous year, according to Colombia's energy ministry.
The Andean country is the world's fifth-largest coal exporter. The fuel is its second top source of foreign exchange after oil.