Two Colombians were killed and five more wounded on Thursday when a jeep carrying explosives for a suspected attack blew up accidentally near Bogota a day after a guerrilla assault killed 19 people.
The blast came during a two-week offensive by the Revolutionary Armed Forces of Colombia that has shattered hopes of talks with the rebels over releasing hostages and eventual peace negotiations with President Alvaro Uribe.
"A vehicle carrying explosives blew up and as a result we have two people dead and five wounded," National Police Col. Wilson Laverde told local radio.
Laverde said the driver was killed in the blast in a residential area near Fusagasuga, 31 miles (50 km) south of Bogota. He said the explosives were intended for an attack, but appeared to have gone off accidentally.
A day earlier hundreds of FARC rebels fired home-made mortars in an attack on a rural police post in their deadliest assault this year on Uribe's US-backed campaign to end Latin America's longest-running insurgency.
Authorities said 17 police and two civilians were killed in Wednesday's rebel assault on Tierradentro, 235 miles (380 km) from Bogota. Eleven rebels were also killed in combat.
The FARC, which has fought a four-decade conflict for a socialist state, is listed as a terrorist group by the United States and the European Union, but the rebels recently asked European governments to remove them from their lists.
"The international community should not even think of considering that the FARC are not terrorists," Uribe said after talking with relatives at a church in Tierradentro.
"If we do not finish off these bandits, they will keep killing our police," said Uribe.
Uribe, who has received millions in US aid to fight the FARC and the drug trade, was re-elected in May after Colombians praised his security crackdown for reducing violence and reclaiming urban areas and highways from the rebels.
He pulled back from possible talks with the FARC over hostages after blaming rebels for a bombing in Bogota two weeks ago. Another car bombing over the weekend at a military base in Villavicencio killed two people.
The FARC has held hundreds of hostages, including three US contract workers kidnapped nearly four years ago after their plane crashed on a drug fumigation mission. The guerrillas want to exchange rebel prisoners for hostages.