A total of six Afghan civilians were killed and two others were injured Saturday morning when a roadside bomb struck a vehicle in southern Uruzgan province, the police said.

"The incident occurred at around 11:15 a.m. local time in Sangar area of Chora district," head of anti-criminal police department in the province, Gulab Khan, told Xinhua.

Violence has been on the rise since Taliban launched an annual spring offensive on May 3.

The insurgent group uses roadside bombs or Improvised Explosive Device (IED) and suicide bombers in their attacks which also inflicts casualties on civilians.

In neighbouring Helmand province, four children were killed and three other children were injured in two separate IED blasts earlier Saturday and Friday evening.

A total of 3,021 Afghan civilians were killed in 2011, an 8 percent rise compared with 2010, according to the United Nations annual report released in Kabul in February.