The talks should continue in the 'spirit of moving towards peace', said High Council for National Reconciliation Chairman Abdullah Abdullah.
A date for the talks, to be hosted in Doha, Qatar, has not been set, but both sides this week have signalled that negotiations could launch soon.
A Taliban delegation is in Islamabad just days after Pakistan reiterated UN sanctions against the group.
The release of 400 militants is seen as the last step before peace talks, but only 80 have been set free so far.
The start of intra-Afghan peace talks hangs on the release of the prisoners, but President Ashraf Ghani said it is 'not possible to release them without consulting the nation'.
The 25-year accord would put Beijing in position to provide an internationally recognised state sponsor of terrorism with military and intelligence assistance.
Washington's approach to the peace deal will be based on certain conditions, said US Special Representative on Afghanistan Reconciliation Zalmay Khalilzad.
Iranian authorities continue to dismiss accusations that Iranian security forces were behind a number of killings of Afghan migrants in past weeks. Evidence suggests otherwise.
Widening of the city's trunk road was completed in 2016, except for the portions where the Iranian consulate building stands, creating an issue of contention between Afghanistan and Tehran.
Veteran diplomat Mohammad Sadiq is expected to help improve Pak-Afghan relations and facilitate the Afghan peace process.