The release of 28 prisoners from various detention centers came a month after an initial 14 others were let go from US and Afghan jails in the wake of a "Peace Jirga," or summit, in June that recommended talks between the government and the Taleban.
The jirga of tribal leaders and other senior figures approved a Karzai plan to reach a peace deal with Taleban moderates, who have helped stage an increasingly violent insurgency since being overthrown in 2001.
Karzai's office, quoting the Afghan justice minister, pledged to soon free 45 more inmates after case reviews.
The jirga also called for the removal of names of militant leaders from United Nations blacklists, as well as peace talks with those who renounced violence.
There was no immediate comment from the Taleban about the latest releases, but the militant group has repeatedly dismissed all peace overtures, saying it will continue to fight until all foreign forces have left the country.
Hundreds of suspected insurgent prisoners without access to lawyers or other rights, have been languishing in jails run by international and Afghan forces for years.
While Karzai's order to review cases, based on the Jirga's proposals, referred only to the roughly 15,000 detainees in Afghan jails, the US military has said the review would also apply to Afghans in US military prisons.
Since January, 114 prisoners have been released from Bagram under new detention review boards set up by Washington last year allowing detainees to contest their incarceration.
However, in a marked shift in policy after years of international criticism, the US allowed the first Afghan detainees at Bagram to stand trial before an Afghan judge and with Afghan defense lawyers.
There are around 1,000 prisoners being held at foreign military detention centers in Afghanistan, more than 800 of those at Bagram, north of the capital.
