A suicide bomb attack in southern Afghanistan has killed at least 21 civilians and injured 13 others. The bomb went off in a crowded market area and a number of children are among those killed.

NATO spokesman Major Quentin Innis says the attack occurred Thursday afternoon in the southern province of Kandahar, outside the provincial capital.

"About 10 to two this afternoon ISAF forces heard an explosion in the center of Panjwayi village about 30 kilometers west of Kandahar," he said.

Local officials say the suspected suicide bomber apparently targeted the International Security Assistance Force, or ISAF, troops but the only causalities were civilians.  NATO commands the ISAF force.

Violence throughout the region has surged in recent months and pro-Taleban militants have stepped up their attacks against international forces in the area.

Also Thursday, in separate attacks two roadside bombs killed a Canadian soldier and wounded four others in Kandahar.

The Canadian was the fourth NATO soldier killed since the alliance took over security operations in the south, the traditional stronghold of the strict Islamist Taleban organization.

NATO officials say the attacks have in no way weakened the alliance's determination or forced them to alter their mission.

Wednesday night a NATO-led sweep in neighboring Helmand province killed or wounded at least 22 suspected Taleban insurgents.

The insurgents oppose the democratic government, which came into power after a U.S.-led coalition ousted the Taleban regime in 2001.