BOGOTA, July 23 (Reuters) - Colombia's Sintramienergetica coal miners' union will return to the negotiating table on Tuesday trying to work out a pay deal, but hopes of avoiding a strike were fading after negotiations late into the night yielded little, a union leader said.
Edgar Munoz, vice president of Sintramienergetica, said a strike action that has been pre-agreed by workers, could come as soon as later on Tuesday or on Wednesday without progress on the company's 4.5 percent pay raise offer or more guarantees for port workers whose jobs could be cut next year.
A strike by workers at the company, which employs around 10,000 at its two mines and port, could instantly cut the flow of coal from Colombia, the world's fourth-biggest exporter, by about one-third if Drummond's output is halted.
"From today we are on maximum alert ... (A strike) could be from today or tomorrow," Munoz told Reuters.
Although the seaborne coal market is currently well supplied, the combination of a strike, if prolonged, and increased demand from purchasers ahead of winter could puncture that surplus and push up coal prices in Europe where much of Colombia's supply is consumed.
Munoz said the labor minister, Rafael Pardo Rueda, would take part in the talks for a second day on Tuesday, underscoring the high stakes of a strike for the government. A month-long stoppage at rival miner Cerrejon in February was one factor behind slower growth in the first three months of the year.
Coal is one of Colombia's biggest exports.