Hamas is accused of using violence to stifle opposition in Gaza
A rights group has accused Palestinian organisation Hamas of killing or maiming alleged collaborators and political opponents in Gaza.
At least 20 people had been killed since the end of last year, Amnesty International stated in a report based on testimony from inside Gaza.
Scores of others had been beaten and injured, the rights group said.
Amnesty says Hamas has been meting out summary justice to those believed to have helped Israeli forces.
The intimidation is said to have started soon after the Israeli army began its operation in Gaza last December and to have continued after its ceasefire in January.
"Hamas forces in Gaza have engaged in abductions, unlawful killings, torture and death threats against those they accuse of 'collaborating' with Israel," says the report.
It says the same violence has been inflicted on "opponents and critics" of the Hamas administration.
Many witnesses and victims are said to be too frightened to come forward.
But one victim told investigators how he had been taken from his home by masked men and shot in both legs.
Some of those killed are said to have been shot dead while receiving hospital treatment.
Amnesty has called for an end to the violence and is urging the Hamas leadership to set up an independent commission to look into its allegations.