A roadside bomb struck a minibus carrying a family of Afghan refugees on Saturday, killing up to 13 people including women and children, officials said. At least 11 of the dead were from the same family, who were returning from Pakistan through the remote province of Zabul, in the volatile south of Afghanistan, when the blast hit. The area borders Pakistan, where Taliban-led militants have hideouts from which they launch violent incursions into Afghanistan. \"A civilian minivan was struck by a roadside bomb in Zanzir area of Shamulzayi district in Zabul province,\" the interior ministry said in a statement. \"As a result of the mine blast, 13 civilians including four women and two children were martyred.\" Deputy provincial governor Mohammad Jaan Rasulyar earlier told AFP that 11 people were killed in the blast at 7:50 am (0320 GMT). He added that the group were all from the same family and were refugees. \"They were en route to Ghazni province from Pakistan through Zabul\'s border area,\" Rasulyar said. Roadside bombs planted by Taliban-led militants, who have been waging an insurgency against foreign forces for nearly 10 years, are a frequent cause of casualties among civilians, who are the biggest victims of the war in Afghanistan. The United Nations said that 2,777 people were killed last year, the highest total since the war started in 2001. The UN also said last month that the number of security incidents in Afghanistan this year since March was 51 percent higher than in the same period last year. Most attacks involved IEDs or armed clashes, it added. Elsewhere in southern Afghanistan, four people were killed Friday by twin landmine blasts in Maruf district of Kandahar province, one of the main focus points of the huge foreign forces\' effort in Afghanistan. \"The first took place at around 9:00 pm killing two civilians who were crossing into a garden,\" said provincial police chief General Abdul Razaq. \"After a crowd of people gathered to collect the bodies from the first blast, the second explosion took place, killing another two.\" The latest civilian deaths are a reminder of the depth of the task facing the Afghan government as it takes increasing responsibility for security following the announcement of the first wave of foreign troop withdrawals. There are around 150,000 foreign troops in Afghanistan, some 99,000 of them from the United States. Limited withdrawals are due to start this month and President Barack Obama has said that 10,000 US troops will leave this year. All foreign combat forces are due to leave Afghanistan by the end of 2014 but the international community stresses it wants a long-term relationship with Afghanistan to support the war-torn, poverty-hit country beyond that. The NATO-led International Security Assistance Force (ISAF) said that a member of the foreign forces was killed in an IED attack in western Afghanistan Saturday.