The captive men were working for oil service companies Tuboscope and Tecnioriente, contracted by the local unit of Occidental Petroleum Corp, when they were snatched last week near the Caricare oilfield in Arauca State.

"The five workers were rescued after combat with fighters from the FARC," local army commander General Rafael Neira said.

He gave no other details.

Violence from the country's long war has eased under President Alvaro Uribe, who has sent troops to retake areas under rebel control. But the kidnappings underscored the threat guerrillas still present in remote, rural areas.

The FARC or Revolutionary Armed Forces of Colombia, has been battered to its weakest in decades and foreign investment, especially in oil and mining, has grown rapidly.

Colombia is Latin America's No. 4 oil producer with output of more than 700,000 barrels per day.

Rebels have often kidnapped civilians for extortion, but they are also holding 24 soldiers and police for political leverage as part of Latin America's oldest insurgency. The FARC plans to free two soldiers to the Red Cross in the next week.