Thirteen Afghan civilians, including four women and nine children, were killed Thursday when a roadside bomb went off in the country's southern province of Uruzgan, a provincial police source said.

"A total of 13 innocent civilians, including four women and nine children, were killed as a roadside bomb struck a car in Siyachoi area of Diarawud district at about 12:15 p.m. local time Thursday," Farid Hayel, a police spokesman in the province, told Xinhua.

The victims were members of the same family, he added.

He said two more people including the driver were severely injured in the attack in the province, some 370 km south of capital Kabul.

The police spokesman blamed the Taliban insurgents for the attack. However, the outfit fighting Afghan government and NATO- led forces has yet to make comment.

Southern Afghanistan, branded as Taliban stronghold, has been the scene of increasing militancy over the past few years.

Eight civilians were killed when a minibus touched off a roadside bomb in neighboring Helmand province on Wednesday. The civilian casualties have increased for the fifth successive year as a total of 3,021 Afghan civilians were killed in 2011, an 8 percent rise compared to 2010, according to a United Nations annual report released in Kabul on Feb. 4.

The UN report attributed 77 percent of the civilian deaths last year to the attacks of Taliban insurgents and other armed groups opposing the Afghan government. Another 14 percent of the deaths were attributed to Afghan and NATO-led forces and 9 percent were unattributed.