By Jack Kimball

BOGOTA (Reuters) - Colombia's FARC rebels blew up the rail line of Colombia's largest coal exporter, Cerrejon, on Thursday, taking the train out of commission for up to four days but not impeding exports, military and company officials said.

The latest attack comes only days after Cerrejon and its workers signed a wage deal to end a strike that paralyzed exports for a month and cost the Andean nation millions of dollars in lost royalties.

"Around 4:45 a.m. (0945 GMT), the train, which was headed toward the coal port of Puerto Bolivar, was attacked with explosives ... which produced the derailment of 17 wagons," Cerrejon said in a statement.

The company, a joint venture between Anglo American, BHP Billiton and Xstrata, did not blame any specific group in the country for the assault.

Juan Carlos Restrepo, vice president of public affairs for the company, said it would take three to four days to repair the damages, but port and mining operations would continue.

The company had enough stocks at the port to continue exporting, he said.

The military accused the Revolutionary Armed Forces of Colombia, known as the FARC, of being behind the attack.

The FARC rebel group and the government are currently trying to reach a peace deal in talks in Cuba.

In late February, assailants blew up four trucks at Cerrejon's Mina Sur mining area in Guajira province. There was another bombing of the railway earlier this year.

In 2012, Cerrejon was attacked seven times.

"We call on the authorities ... to redouble efforts to ensure our safety and that of the company," the Sintracarbon union said in a statement.

On Monday, Cerrejon and its labor union signed a three-year wage agreement ending a walkout by workers that started on February 7 and forced the company to declare force majeure on some cargoes.

Guajira province is known as a Wild West-type region in Colombia where smugglers and drug runners use the long border with neighboring Venezuela as well as access to the Caribbean sea to ship their illegal wares.

The flow of contraband through the region is believed to date back to the 16th century when local indigenous people sold pearls to passing European merchants.

The FARC has had a limited presence in Guajira after the entrance of right-wing paramilitary groups in the 2000s pushed the guerrillas into remote areas of the province.

According to one study, the main actors in the region are the new criminal gangs that emerged from the demobilization of paramilitary groups and the breakup of the traditional cartels.

Oil and mining operations have been targets for armed groups as well as labor unrest, although security for businesses has vastly improved since a U.S.-backed offensive against anti-government guerrillas and drug gangs was launched in 2002.

Improved security has helped attract billions of dollars in new investment as explorers push into more areas in search of minerals and oil. In 2012, Colombia brought in $16 billion in foreign investment, up from around $2 billion in 2002.

(Reporting by Jack Kimball; Editing by Vicki Allen and Todd Eastham)