KABUL — An official says four would-be suicide bombers have been killed in a premature explosion in southern Afghanistan.

Deputy provincial police chief Fazel Ahmad Sharzad says the suspects were traveling from the Panjway district to Kandahar when the blast occurred about 8 p.m. Wednesday.

He says the men were planning an attack in Kandahar but explosives in the car detonated before they reached the city. He didn't say Thursday what the target may have been.

The U.N. says suicide bombings and other attacks were the main cause of civilian deaths last year in Afghanistan. Violence in the south has intensified with a stepped up effort by the international community to rout the insurgents. (AP)