The true number of those released across the country is difficult to verify, and many were freed only after signing documents promising not to re-offend.
At least 110 of those pardoned have since been re-arrested, according to the AAPP.
“Some were... re-arrested as soon as they arrived home,” it said in a statement Thursday.
“Some others were told they were on the released list, taken to the jail entrance, only to be taken back to prison in the face of additional charges.”
Myanmar authorities released more than 2,000 anti-coup protesters from prisons across the country in June, including journalists critical of the military government.
Those still in custody include the American journalist Danny Fenster, who has been held since being arrested on 24 May.
The most recent amnesty comes with the military under increasing pressure to engage with its opponents, nearly nine months after seizing power.
Last week the Association of Southeast Asian Nations (ASEAN) decided to exclude junta leader Min Aung Hlaing from an upcoming summit of the 10-country bloc over doubts about his commitment to defusing the bloody crisis.
The United States welcomed the rare move by ASEAN—long criticised as toothless—Derek Chollet, counselor of the State Department, told reporters on Thursday.
Chollet was speaking during a tour to the region to consult with US allies on further ways to put pressure on the junta.
The coup snuffed out the country’s short-lived experiment with democracy, with civilian leader Aung San Suu Kyi now facing a raft of charges in a junta court that could see her jailed for decades.