By Jack Kimball
BOGOTA (Reuters) - Unknown assailants bombed the rail line of Colombia's largest coal exporter on Thursday, knocking 17 wagons off the rails, the Cerrejon coal company said.
The latest attack comes only days after Cerrejon and its workers signed a wage deal to end a strike that had paralyzed exports for a month and cost the government millions of dollars in lost royalties.
"Around 4:45 am (0945 GMT), the train, which headed towards the coal port of Puerto Bolivar, was attacked with explosives ... which produced the derailment of 17 wagons," Cerrejon said in a statement.
The company, which is a joint venture between Anglo American, BHP Billiton and Xstrata, did not blame any specific group in the area for the assault.
The security forces, however, usually accuse the Revolutionary Armed Forces of Colombia, known as the FARC, for these types of attacks. Rebels and the government are currently trying to reach a peace deal in talks in Cuba.
"We call on the authorities ... to redouble efforts to ensure our safety and that of the company," the Sintracarbon union said in a statement.
In late February, assailants blew up four trucks at Cerrejon's Mina Sur mining area in Guajira province.
On Monday, Cerrejon and its labour 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.
The Guajira province is known as a Wild West-type region in Colombia where smugglers and drug runners use the long border with neighbouring Venezuela as well as access to the Caribbean sea to ship their illegal wares.
Contraband in 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 the 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 area 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 labour unrest, although security for business 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)