Several Taliban gunmen stormed the school in the northwestern city of Peshawar last month, killing 150 people, mostly children, in the country’s deadliest ever militant attack.
The December 16 attack on the Army Public School, which drew international condemnation, prompted a bout of national soul-searching even in a country used to high levels of violence.
On Saturday an Afghan security source, speaking on condition of anonymity, confirmed to AFP that his force had recently made five arrests, after Pakistan supplied information to Kabul.
The official said the men, who were not Afghan nationals, were arrested in the troubled border areas between the two countries.
They were accused by Pakistan of aiding the Peshawar school attackers, he said, insisting that the investigation by the Afghan security agencies had not yet established the suspects’ direct association with the attack.
Pakistani officials declined to immediately comment.
Afghanistan has been gripped by a fierce Taliban-led insurgency since 2001 when a US-led invasion toppled their hardline Islamist regime for sheltering the then Al-Qaeda leader Osama Bin Laden.
The US-led coalition forces ended their combat mission on December 31 after 13 years of fighting, in spite of a continuing Taliban insurgency.
About 17,000 US-led foreign troops will remain deployed this year, focusing on training the Afghan police and army and conducting a limited counter-terrorism mission. -AFP