Five civilians were killed Saturday morning when a roadside bomb struck their vehicle in Afghanistan's Helmand province, 555 km south of capital city of Kabul, a spokesman for the provincial government said.

"A civilian mini-bus touched off a roadside bomb at around 10: 00 a.m. local time Saturday in Nahri Sarraj district triggering a powerful blast that left five civilians dead," Daud Ahmadi told Xinhua.

The casualties include two men and three women, he said, adding the bomb was placed by Taliban insurgents to target security forces.

However, the Taliban has yet to make comments.

As part of its tactics the militant group has resorted to suicide attacks and roadside bombings which often claim civilians.

A total of 18 civilians were killed in a similar incident in the same district on July 29.

A total of 1,462 Afghan civilians have been killed in the first half of 2011 which indicates, a 15 percent rise in non-combatants' deaths compared with the same period in 2010, according to the United Nations mid-year report released in Kabul on mid-July this year.