KABUL     -    Nine children were killed when a planted roadside bomb exploded as they walked to school in a northeastern province of Afghanistan, government and police officials said.

The blast happened in Darqad district of Takhar province on Saturday, when the children, aged between eight and 11, stepped on the bomb planted on a road in a Taliban-controlled village.

“In the morning on roadside, nine children were killed in a landmine blast placed by the Taliban. Three children, who were part of the group, are missing,” Jawad Hejri, a spokesman for the Takhar provincial governor, told Al Jazeera.

No group has claimed responsibility for the blast, and the Taliban did not immediately respond to a request for comment following the deaths the children, the latest victims in a growing toll of civilian casualties in the war.

“This area is under Taliban control and since security forces launched attacks to clear it, the Taliban have planted anti-personnel mines,” Khalil Asir, a spokesman for the provincial police, told Reuters news agency.

The children - eight boys and a girl aged between seven and 10 - accidentally stepped on a deliberately-planted mine, officials said.

“At 8.30am (04:00 GMT) this morning, tragically, nine school children were martyred in a landmine blast,” Jawad Hejri told news agencies. He alleged that the roadside device had been planted by the Taliban, which had taken control of Takhar Province for several weeks before Afghan forces recently regained control.

In May, a landmine killed seven children and wounded two more in the southern province of Ghazni.

Last month, the United Nations released a report saying an “unprecedented” number of civilians were killed or wounded in Afghanistan from July to September this year. The figures - 1,174 deaths and 3,139 injuries from July 1 until September 30 - represent a 42 percent increase compared to the same period last year.

A month earlier, seven children were killed and 10 more wounded in the eastern province of Laghman when a mortar shell exploded while they were playing with it.

The Taliban often use roadside bombs and landmines to target Afghan security forces, but the lethal weapons also inflict casualties on civilians.

Years of conflict have left Afghanistan strewn with landmines, unexploded mortars, rockets and homemade bombs - and many are picked up by curious children.