In the most recent incident, on 22 June, a NATO air strike in the southern province of Helmand killed 25 civilians, including nine women and three young children, AFP news agency reported quoting local police. The children were aged between six months and two years old, the report added.
UN Secretary-General Ban Ki-moon has strongly condemned the recent spate of violence in Afghanistan.
"The Secretary-General condemns these acts in the strongest possible terms, which reflect an inexcusable disregard for the value of human life," his spokesperson said in a statement on 20 June.
The statement added that "over the past few days, there has been a spate of similar attacks in other parts of the country, reportedly claiming the lives of dozens of civilians, including 11 children".
On 19 June, Radhika Coomaraswamy, UN Special Representative for Children and Armed Conflict, called upon all sides of the conflict "to take all necessary steps to protect children and to respect international humanitarian law".
Afghan children are affected by the armed conflict in their war-ravaged country in many different ways, according to Afghanistan's human rights commission (AIHRC).
"Children are used as soldiers, deprived of education, killed or wounded, forced to migrate, and divested of many other securities," Najibullah Babrakzai, a children protection officer for AIHRC, said.
"We call upon the Taliban, US military, ISAF [International Security Assistance Force] and all other parties involved in the conflict to reduce the impact of their military operations on Afghan children," said Babrakzai.
Over the past few weeks, fighting has claimed the lives of many civilians, including children, observers say.
Children killed in heavy clashes
On 18 June, in heavy clashes between Taliban insurgents and NATO-led ISAF forces in the Chora district of the southern province of Urozgan, scores of civilians, including children, were killed or injured, according to local officials.
Mawlawi Hamdullah, head of Urozgan's provincial council, told reporters on 19 June that up to 60 civilians were killed in the military operation.
Rabia, 4, and her mother Bibi Raziqa were wounded in the fighting and were admitted to a hospital in Tirinkot, the provincial capital of Urozgan. "The whole night she cried for her mother," said Sardaar Mohammad, Rabia's uncle.
But Major John Thomas, a spokesman for ISAF in Kabul, told IRIN that almost all of those killed in that operation were insurgents.
On 15 June, at about 11:15am local time, a suicide bomber detonated his explosives in Tirinkot, which culminated in the death of 11 children, eight to 15 years old, and one soldier, the UN confirmed.
"I have one question: Who on the side of those calling themselves 'Taliban' will take responsibility for these crimes?" asked Chris Alexander, Deputy Special Representative of the UN Secretary General for Afghanistan.
At least seven other children died on the night of 17 June, when US warplanes bombed an Islamic school in Zarghun Shah District in the southeastern province of Paktika, a US military press release confirmed.
"We did not know that Americans would bomb the school," Akram Khpalwak Paktika's governor, told IRN, adding there were fears that the place was used as a safe haven by the Taliban.
On 12 June, gunmen suspected to be associated with Taliban insurgents opened fire on schoolgirls in the central Logar province killing two students - 12-year-old Shukria and 13-year-old Saadia - and wounding three others.
"We are neither with the Taliban nor with the government. But why are our sons and daughters killed? Why do both sides kill us?" asked Sobhanullah, who lost his 10-year-old daughter in the suicide bomb attack on 15 June.