Afghan officials, hopeful that direct contacts with top Taliban commanders could give them strong leverage in any peace talks, have long urged Pakistan for access to prisoners.
"We aren't too certain whether they can play an important role in peace negotiations but it is a positive gesture from Pakistan in helping peace efforts," an Afghan official told Reuters. He said it was not clear when the release would occur.
A senior Pakistani army official said it had not yet been decided if the former Afghan Taliban second in command, Mullah Abdul Ghani Baradar, would be released.
Afghan officials have identified him as a figure who may still command enough respect to persuade the Taliban to pursue peace after more than a decade of fighting US-led NATO and Afghan forces.
A political settlement between the Afghan government and the insurgents is widely seen as the best way of delivering stability to the country before most NATO combat troops pull out at the end of 2014.
The Pakistani army official declined to give any information about who was going to be released saying details had yet to be worked out.
The decision to release the prisoners was a major achievement for Afghanistan's High Peace Council, which is in Islamabad to push for Taliban releases and has been struggling to ease mistrust between the Taliban and the Kabul government.
Afghanistan's government has failed to secure direct talks with the Taliban and no significant progress is expected before 2014, when most NATO combat troops withdraw, a senior Afghan official closely involved with reconciliation efforts told Reuters last week.
There has also been little progress on other fronts. The Taliban said in March they were suspending nascent peace talks with the United States held in Qatar, blaming "erratic and vague" US statements.
Even if the release of the Afghan Taliban prisoners does not produce breakthroughs, it could improve Pakistan's image and bolster its argument that it is committed to stabilising Afghanistan.
Afghan officials have often seen Pakistan as a reluctant partner in attempts to broker talks with the Taliban.
Afghan and US officials accuse Pakistan of using insurgent groups, including the highly lethal Haqqani network, as proxies in Afghanistan to counter the influence of rival India. Pakistan rejects that.
Afghanistan has been known to want access to Taliban leaders belonging to the so-called Quetta Shura, or council, named after the Pakistani city where they are believed to be based.
Pakistan has consistently denied giving sanctuary to insurgents and says no Taliban leaders are in Quetta.