Leftist rebels ambushed a group of soldiers Tuesday who were protecting civilians in southern Colombia, killing 28 in the deadliest rebel attack in a year marked by hundreds of military deaths, officials said.
About 400 rebels with the Revolutionary Armed Forces of Colombia, or FARC, surprise attacked 80 troops near Vista Hermosa, 105 miles south of Bogota, said brigade commander Col. Carlos Ramirez.
Initial reports by several military officials indicated the soldiers were protecting government workers during a coca eradication effort when the rebels attacked.
The troops, however, remained in the area near Vista Hermosa to provide security to civilians who were being threatened by the FARC, which controls cocaine production in the area, he said.
At least five other soldiers were injured, three seriously, the Colombian army said. One soldier remains unaccounted for, and was perhaps kidnapped, said the minister.
"The Army has set forth an operation to pursue the attackers," said a ministry statement.
Since the beginning of the year, more than 600 government forces, including military and police, have been killed by the FARC or other illegal, armed groups, according to government statistics.
Among other major rebel attacks this year, several hundred FARC fighters in June launched an assault against a small military base in southern Putumayo, killing 22 soldiers. And in February, the FARC used homemade rockets to attack a marine outpost on the Iscuande River in southwest Colombia, killing 16 marines.
The FARC, which funds itself mainly through drug trafficking and kidnapping, is considered a terrorist organization by the United States and the European Union.
Founded 40 years ago and with at least 12,000 fighters, the FARC is the country's main rebel group. Its expressed aim is to fight for social revolution and redistribute wealth in this country of 44 million people.
Hard-line President Alvaro Uribe, backed by billions of dollars in U.S. aid to fight drug trafficking and rebels, launched a military offensive against the FARC in the southern region where Tuesday's attack occurred. Colombia is the world's leading producer of cocaine, and supplies up to 90 percent of the U.S. market.
Despite the offensive, the FARC continues to have a strong presence in the region.
Meanwhile, the Organization of American States said Tuesday that right-wing paramilitary groups were behind an apparent massacre that left at least eight people dead in early December in the northern Curumani region.
In a preliminary report, the OAS said eyewitnesses reported that some 150 fighters of the Northern Bloc of the United Self-Defense Forces of Colombia, or AUC, took hostage and killed at least eight people after clashes with leftist guerrillas.
The paramilitary faction's leader, who goes by the alias "Jorge 40," in a statement denied that his group was responsible for any massacre. He said those killed were leftist rebels who first attacked his group.