Four suspected Taliban (search) fighters died when a bomb they were laying on a road regularly used by Afghan soldiers exploded prematurely, an official said Saturday.

Meanwhile, suspected drug smugglers fatally shot five Afghan soldiers, extending a wave of violence in southern Afghanistan since the ratification of the country's first post-Taliban constitution last Sunday.

The bodies of four men were found on a road between Musa Qala and Sangin in Helmand province, some 70 miles northwest of the former Taliban stronghold of Kandahar (search).

Provincial government spokesman Mohammed Wali Alizai (search) told The Associated Press that the men were carrying documents containing satellite phone numbers that showed they had links to the Taliban. He gave no further details.

"They were Taliban trying to lay a lay a bomb for the Afghan soldiers that often patrol this area," Alizai said.

Four time bombs and two wireless sets were found near the bodies.

The incident came four days after a bomb in Kandahar city killed 15 Afghan civilians, most of them children, and a shooting in northern Helmand left 27 civilians dead.

The violence underlines the failure of U.S. and Afghan forces to crush the Taliban two years after their ouster, and threatens the timetable for summer elections under the new constitution.

More violence broke out Saturday when a group of 20-25 armed men attacked a remote army border post near Shorabak, in Kandahar province. Of the ten soldiers stationed there, five were killed and two injured, deputy governor Mohammed Hanas Khan told AP.

The outnumbered soldiers "had no chance to fire back," Khan said, adding that the attackers fled before reinforcements could arrive.