The majority of members at two unions of Colombian coal miner Cerrejon voted to strike because of a dispute over pay and benefits in their contract, a union leader told Reuters. A strike at Cerrejon, which is owned equally by BHP, Anglo American and Glencore, could cut the company’s coal production and sales outside of Colombia, the fifth biggest coal exporter in the world.

“With a vote strongly in favor of industrial action, the members of the biggest union have just declared a strike at Cerrejon,” Igor Diaz, president of the larger Sintracarbon union, said in a message to Reuters, adding that 98.8% of the 3,631 votes supported downing tools.

A start date for the strike hasn’t been decided, but could begin in 10 days. The 20-day negotiation period between the miner and Sintracarbon ended on February 15. At that time, both agreed to a further 20 days of negotiations, which ended on March 6. Sintracarbon and Sintracerrejon, the minority union, called for their members to vote between striking and seeking arbitration.

A source from Cerrejon told Reuters that despite the decision by the unions, talks will continue to try to avoid the strikes.