Taliban fighters beheaded two boys aged 10 and 16 as a warning to villagers not to cooperate with the Afghan government, local officials said.
The boys, named Khan and Hameedullah, had travelled to Afghan army and police checkpoints near their home in the southern province of Kandahar, scrounging for leftover food to bring to their families, the officials said.
"The boys were on their way back ... when they were stopped by Taliban insurgents who beheaded them," the chief of Zhari district, Jamal Agha, told Reuters. "Both of them were innocent children and had nothing to do with government or foreigners."
The militants have beheaded dozens of people in the last two years, accusing them of aiding the government and its foreign backers led by the United States.
A Taliban spokesman, Qari Yousuf Ahmadi, said the group was not involved in the boys' killings.
The Kandahar governor's spokesman, Javid Faisal, said the incident occurred on Sunday. Several hours later their bodies and severed heads were left in their village, he said.
Kandahar is the birthplace of the Taliban and one of Afghanistan's most restive provinces.
In July last year in the same district, a 16-year-old boy accused by the Taliban of spying for the government was beheaded and skinned. The next month, a girl aged six and a boy of 12 were kidnapped and beheaded in separate incidents in Kandahar and the east of the country.
Such incidents highlight the difficulty that Taliban leaders have in enforcing discipline across an estimated 20,000 fighters spread from Afghanistan to Pakistan.
The leadership is trying to improve the group's image in case it wants to push forward tentative reconciliation steps and perhaps even enter mainstream politics. But some militant units have proved hard to control, roaming the countryside and killing or maiming those they deem immoral.
The beheading occurred the day before seven Taliban insurgents including suicide bombers attacked country's international airport in the capital, Kabul.
Also on Monday, six insurgents with suicide vests and heavy guns attacked a government compound in the provincial center of Zabul, wounding at least 18 people.
Concerns are mounting over how the 352,000-strong Afghan security forces will cope with an intensifying Taliban insurgency once most foreign troops leave by the end of next year.