KABUL (AFP) - Two men were killed when a bomb exploded as they were planting it outside a regional electoral campaign office of Afghanistan's US-backed President Hamid Karzai, an official said.
The bombers had targeted Karzai's office in the capital of Logar province, Pul-e-Alam, some 60 kilometers (38 miles) southeast of the capital Kabul, on Thursday night, he said.
"Two men who wanted to plant a bomb outside President Karzai's electoral office died as the bomb went off," provincial governor Mohammed Aman Hamimi told AFP.
"One of the bombers was beheaded with his own bomb and the second died soon after of his wounds."
It was the fourth incident this week in which would-be bombers have been killed or injured by their own explosives as the turbulent country heads for its first presidential elections on October 9.
On Tuesday, a man was killed in southeastern Khost province when a rocket strapped to his motorbike detonated because of the heat of the engine. A passerby was injured.
On Wednesday, a man carrying a bomb on his bicycle in southern Kandahar city, some 460 kilometers (290 miles) south of the capital Kabul, was injured when the device exploded accidentally.
The same day, another man was injured when his bomb exploded in Qalat in the south.
On Friday, a would-be bomber died as his bomb went off accidentally near a mosque in southeastern Paktica province.
Militants loyal to the former Taliban regime, ousted by the US-led invasion in 2001, have vowed to step up attacks in a bid to disrupt the elections.
On Saturday, NATO-led peacekeepers announced that 25 suspected militants were arrested in a dawn raid in Kabul. An Afghan intelligence source told AFP a shipping container holding explosives, rockets and a suicide-bombing vest had been seized.