GAZA CITY, Gaza Strip, (AP) – The militant Hamas group launched a campaign to arrest suspected collaborators with Israel in the Gaza Strip, detaining five in overnight raids, a Hamas security official said Wednesday.

The raids began after a two-month amnesty for collaborators expired and just three months after two collaborators were executed.

Collaboration is viewed as an especially egregious offense in Palestinian society.

The Hamas official said suspects would go to trial, adding, “We are not going to show any mercy to those involved in spying on our people.”

He spoke on condition of anonymity because he was not authorized to discuss the arrests.

Israel’s domestic Shin Bet security service maintains a network of informers in the West Bank, Gaza Strip and east Jerusalem. Collaborators are often recruited through blackmail, payment or the promise of entry and work permits to Israel.

In April, Hamas executed two accused collaborators, dumping their bullet-riddled bodies outside a Gaza hospital. It was the first time the Hamas government carried out the death penalty since the Islamic militant group violently seized power in Gaza three years ago.

The killings drew condemnations from human rights groups that have criticized the Hamas military tribunals, saying they often rely on confessions obtained through torture.

Amnesty International and other human rights organizations have also accused Hamas gunmen of killing suspected collaborators during the chaos surrounding Israel’s Gaza offensive in the winter of 2008-2009.