UPDATE 2-Workers strike at Colombia's top coal exporter

* Strike was called before Friday cut-off date

* Union, Cerrejon disagreed on compensation and benefits

* Coal sector faces other problems in major producers

BOGOTA, Feb 7 (Reuters) - Workers at Colombia's largest coal exporting company Cerrejon began a strike on Thursday, after the two sides failed to reach an agreement during last-minute talks on wages and benefits.

The dispute adds to problems in the Andean nation's coal industry, which is facing an environmental inquiry into Drummond, the second-largest exporter, and a dispute at a mine owned by a Goldman Sachs Group Inc affiliate.

In total, about 85 percent of Colombia's daily coal production will be shut down as a result of the sector's recent problems, according to calculations by Reuters and industry sources.

"At 3 p.m. (2000 GMT) exactly, the strike began," Orlando Cuello of the Sintracarbon union told Reuters.

Cerrejon said the strike would cause the economy to lose about $3 million daily.

"For Cerrejon, Sintracarbon's decision to launch a strike is unfounded and irresponsible," the company said in a statement.

"After a thorough analysis of the arguments raised by union leaders, both at the negotiating table and in their public statements, Cerrejon is not clear on what are the real motivations that led them to order the cessation of activities."

Laborers at Cerrejon, a joint venture between BHP Billiton , Anglo American and Xstrata, voted on Jan. 29 to strike. By law, however, they could not walk out on the first or last of a 10-day window, which ended on Friday.

During the previous wage talks in 2011, Cerrejon and the union were able to reach agreement. The last time Cerrejon workers had a strike was in the 1990s.

Prices for coal delivered into northwestern Europe moved up slightly on Thursday as did near-term swaps on concerns about supply from Colombia.

DRUMMOND SUSPENSION

Ten years of U.S.-backed military operations against leftist rebel groups have opened up large swathes of territory to new investment and helped secure areas where exploration and production were already in progress.

Like other commodity-exporting countries, Colombia has faced increased environmental and social demands, which some analysts say have replaced guerrilla activity as the main risk for mining investors in the world's fourth-largest coal exporter.

The coal sector faced a series of worker disputes last year, including a strike at the country's main coal railway, that dragged down growth in the third quarter as stoppages bit into exports and regional economies.

On Wednesday, Colombia suspended loading at Drummond's port after a coal barge nearly sank in bad weather last month, a government agency said. The suspension will be lifted once Drummond presents a contingency plan.

Drummond Ltd vowed on Thursday to take "corrective" measures at its Caribbean port.

Drummond, which is 20 percent owned by Japan's Itochu Corp , produces about 80,000-90,000 tonnes per day from its mines in the northern Cesar province. The company will also hold wage discussions with workers later this year.

Nearby, Goldman Sachs affiliate Colombian Natural Resource's La Francia thermal mine has remained shut since late January due to a pay dispute with the operator, union officials said.

The mine produces around 10,000-20,000 tonnes per day.

Nationally, Colombian production is around 220,000-250,000 tonnes daily.

Latin America's fourth-largest economy wants to boost coal output this year to around 98 million tonnes mainly due to expansion projects at Cerrejon, Drummond and Glencore's Prodeco unit from around 90 million tonnes last year.