At least 19 soldiers were killed over the weekend in separate clashes with rebels in Colombia, the country's president said. President Juan Manuel Santos reported attacks by the Revolutionary Armed Forces of Colombia, commonly known as the FARC, in Arauca and Caqueta. In Arauca, which borders Venezuela, rebels ambushed a group of soldiers guarding an oil pipeline. Fifteen soldiers were killed and 12 rebels were captured, Santos said. Another four soldiers were killed in Caqueta, which is in the south of the country. "The instructions to our forces are as follows: Don't stop shooting, even for an instant until we reach the end of the conflict," the president said, according to his office quoted by CNN. Santos vowed operations will continue until those responsible are held to account. The violence comes amid peace talks between the government and the FARC. The two sides have been at war since the 1960s.