Islamabad: Pakistan has said no "technical traces" of telephonic contacts between the Kabul university attackers and people on its side of the border could be found and sought more evidence from the Afghan government.
Afghanistan had blamed militants using Pakistan soil to launch the attack at the American University in Kabul that killed 16 people, including eight students, and left 50 people injured on Wednesday.
Afghan President Ashraf Ghani called Pakistan army chief General Raheel Sharif on Thursday and urged for action against the attackers' accomplices, Dawn reported.
But General Sharif told the Afghan leader that there were no "technical traces" to prove the telephonic conversation with militants in Pakistan with the attackers.
Gen Sharif assured Ghani of "all-out cooperation" in investigating the role of Pakistan-based elements in the attack, but stressed that it could happen only after Afghans provide "more information".
The Afghan government shared three mobile phone numbers allegedly operating on the Pakistani side of the border, which it claimed had remained in contact with the attackers.
Subsequently, the Pakistan Army initiated a combing operation along the Pak-Afghan border near Chaman to find the suspected persons. "We searched, but no-one was found during the operation," the security sources said.
"Our evaluation of the evidence provided and outcome of Combing Operation so far, has shown that all Afghan SIMs used during the attack were from a network owned and operated by an Afghan company whose spillover signal affects some areas along the Pak-Afghan border," the Inter-Services Public Relations said in a statement.
Pakistani intelligence agencies are, however, continuing with the evaluation of the intelligence shared by Afghanistan after the attack.
The Foreign Office had earlier condemned the attack.
The high-level conversation took place as US Special Envoy to AfPak Richard Olson, Special Assistant to the US President Peter Lavoy and Commander of Resolute Support Mission in Afghanistan Gen John Nicholson visited Islamabad, where they held meetings civil and military leadership.