At least 27 people, most of them civilians and one a provincial mayor, were killed in a spate of attacks in Afghanistan on Monday, officials said. Violence has sharply increased in recent years in Afghanistan despite the growing number of NATO and US troops, more than seven years on since the Islamist Taleban were ousted from power by US-backed Afghan forces. In the bloodiest incident on Monday, 12 civilians – four women, two children and six men – were killed by a roadside bomb that struck as they drove in a tractor in the Shamolzai district of southern Zabul province, said Mohammad Wazir, district chief of Shamolzai. “This was a mine newly planted by the Taleban,” he said. A while later, Taleban guerrillas ambushed a convoy of a security firm in another area of Zabul, killing six Afghan security guards in the convoy and two civilians nearby, Ghulam Jailani, a senior provincial police official, said. Earlier Monday, a provincial mayor was among seven people killed by a teenage suicide bomber who blew himself up at the gate of a municipal administration building in the eastern province of Laghman, the Interior Ministry said. Three body guards and three civilians were killed along with the province's mayor, Mohammad Rahim, the Interior Ministry said. A spokesman for the provincial governor's office, Sayed Ahmad Sopai, said 10 people were also wounded, including three women. He said the suicide bomber was identified as a 14-year-old boy from Paktika province further south. There was no immediate claim of responsibility for any of the attacks. The Taleban have frequently used suicide bombers to strike government buildings as part of their campaign to drive foreign forces from Afghanistan.