GAZA CITY - Gaza’s Hamas rulers hanged three men they accused of collaborating with Israel Thursday, fulfilling vows of revenge for the mysterious killing of one of their commanders last month.

The men, dressed in red prison jumpsuits, were shackled hand and foot and hooded as they were put to death at an excercise ground inside a police facility, an AFP correspondent reported.

Senior Hamas officials, representatives of other Gaza-based groups and a few journalists observed the hangings.

Hamas says that the Israeli intelligence agency Mossad and its Palestinian “collaborators” killed Mazen Faqha in the Palestinian territory on March 24.

The men who were hanged on Thursday were not implicated in his killing but were accused of past acts of “treason and collaborating,” a Hamas interior ministry statement said.

“The military court in Gaza sentenced them to death by hanging, and the decision was upheld by each military appeals court and the high military court,” it said.

They were aged 55, 42 and 31, the ministry said but did not name them.

Human Rights Watch condemned the executions.

“The death penalty is a barbaric practice,” it said in a statement.

“The abhorrent executions by Hamas authorities of three men in Gaza deemed to be collaborators project weakness, not strength.

“Hamas authorities will never achieve true security or stability through firing squads or by the gallows, but rather through respect for international norms and the rule of law.”