The 149-page report, which was published on Tuesday and is based on interviews with former Palestinian detainees and their relatives, alleges the rival factions have “established machineries of repression to crush dissent”.
It adds that security forces often taunt, threaten, beat, and put detainees in painful stress positions.
The report cites interviews with 147 witnesses and reviews photographic and video evidence, medical reports and court documents.
HRW says that in recent years both PA and Hamas security forces have carried out scores of arbitrary arrests for peaceful criticism, particularly on social media, among independent journalists, on university campuses, and at demonstrations.
“Palestinian authorities often rely on overly broad laws that criminalize insulting ‘higher authorities’, creating ‘sectarian strife’, or ‘harming the revolutionary unity’ to detain dissidents for days or weeks, only to release most of them without referring them to trial, but often leaving charges outstanding” the report says.
Both the PA and Hamas have denied the claims made by HRW.
Click here to read the report in full.